diff --git a/SRV/UETAG/PlatUeIdentity.robot b/SRV/UETAG/PlatUeIdentity.robot
index b1830b1fc711f85213b331b3f7b6dbfa5a8928e7..17de4cd92ce4ac741a694545ef255965dac13b88 100644
--- a/SRV/UETAG/PlatUeIdentity.robot
+++ b/SRV/UETAG/PlatUeIdentity.robot
@@ -12,7 +12,7 @@ Default Tags    TC_MEC_SRV_UETAG
 
 
 *** Test Cases ***
-Get UeIdentity tag information
+Get UE Identity Tag information
     [Documentation]   TC_MEC_SRV_UETAG_001_OK
     # Check that the IUT responds with the information on a UE Identity tag when queried by a MEC Application
     # Reference ETSI GS MEC 014 V1.1.1, clause 7.3.3.1
@@ -31,9 +31,43 @@ Get UeIdentity tag information
     Check HTTP Response Body Json Schema Is   ueIdentityTagInfo
     #Log    Check ueIdentityTagsList for ${UE_IDENTITY_TAG} element
     Should Be Present In Json List    ${response['body']['ueIdentityTagInfo']['ueIdentityTags']}    ueIdentityTag    ${UE_IDENTITY_TAG}
-    Log    ${UE_IDENTITY_TAG} found
 
-Register a UE Identity tag
+Bad Request error on UE Identity Tag registration
+# FIXME Which IE protocol should be invalid?
+    [Documentation]   TC_MEC_SRV_UETAG_001_BR
+    # Check that the IUT responds with an error when a request with incorrect parameters is sent by a MEC Application
+    # Reference ETSI GS MEC 014 V1.1.1, clause 7.3.3.1
+    # Reference https://forge.etsi.org/gitlab/mec/gs014-ue-identity-api/blob/master/UEidentityAPI.yaml#/definitions/UeIdentityTagInfo
+
+    [Tags]    TP_MEC_SRV_UETAG_001_BR    TP_MEC_SRV_UETAG
+
+    Set Headers    {"Accept":"application/json"}
+    Set Headers    {"Content-Type":"application/json"}
+    Set Headers    {"Authorization":"Basic YWxhZGRpbjpvcGVuc2VzYW1l"}
+    Set Headers    {"Content-Length":"0"}
+    Get    /exampleAPI/ui/v1/${APP_INSTANCE_ID}/invalid/ue_identity_tag_info?ueIdentityTag=${UE_IDENTITY_TAG}
+    ${output}=    Output    response
+    Set Suite Variable    ${response}    ${output}
+    Check HTTP Response Status Code Is    400
+
+Not Found error on UE Identity Tag registration
+    [Documentation]   TC_MEC_SRV_UETAG_001_NF
+    # Check that the IUT responds with an error when a request for an URI that cannot be mapped to a valid resource URI is sent by a MEC Application
+    # Reference ETSI GS MEC 014 V1.1.1, clause 7.3.3.1
+    # Reference https://forge.etsi.org/gitlab/mec/gs014-ue-identity-api/blob/master/UEidentityAPI.yaml#/definitions/UeIdentityTagInfo
+
+    [Tags]    TP_MEC_SRV_UETAG_001_NF    TP_MEC_SRV_UETAG
+
+    Set Headers    {"Accept":"application/json"}
+    Set Headers    {"Content-Type":"application/json"}
+    Set Headers    {"Authorization":"Basic YWxhZGRpbjpvcGVuc2VzYW1l"}
+    Set Headers    {"Content-Length":"0"}
+    Get    /exampleAPI/ui/v1/${NON_EXISTENT_APP_INSTANCE_ID}/ue_identity_tag_info?ueIdentityTag=${UE_IDENTITY_TAG}
+    ${output}=    Output    response
+    Set Suite Variable    ${response}    ${output}
+    Check HTTP Response Status Code Is    404
+
+Register a UE Identity Tag
     [Documentation]   TC_MEC_PLAT_UETAG_002_OK
     # Check that the IUT registers a tag (representing a UE) or a list of tags when commanded by a MEC Application
     # Reference ETSI GS MEC 014 V1.1.1, clause 7.3.3.2
@@ -41,11 +75,51 @@ Register a UE Identity tag
 
     [Tags]    TP_MEC_SRV_UETAG_002_OK    TP_MEC_SRV_UETAG
 
+    Set Headers    {"Accept":"application/json"}
+    Set Headers    {"Content-Type":"application/json"}
     Set Headers    {"Content-Type":"application/json"}
     Set Headers    {"Authorization":"Basic YWxhZGRpbjpvcGVuc2VzYW1l"}
     # Preamble: Check that the user tag is not registered
     Check User Identity Tag state    ${UE_IDENTITY_TAG}    UNREGISTERED
     # Test Body: Register the tag user and check that the IUT has registered the tag user
-    Post    /exampleAPI/ui/v1/${APP_INSTANCE_ID}/ue_identity_tag_info    {"ueIdentityTags":[{"ueIdentityTag":"UeTagA","state":"REGISTERED"}]}
+    Post    /exampleAPI/ui/v1/${APP_INSTANCE_ID}/ue_identity_tag_info    {"ueIdentityTags":[{"ueIdentityTag":"${UE_IDENTITY_TAG}","state":"REGISTERED"}]}
+    ${output}=    Output    response
+    Set Suite Variable    ${response}    ${output}
     Check User Identity Tag state    ${UE_IDENTITY_TAG}    REGISTERED
-    Log    ${UE_IDENTITY_TAG} was registered successfully
+
+Bad Request error on invalid state
+    [Documentation]   TC_MEC_PLAT_UETAG_002_BR
+    # Check that the IUT responds with an error when an unauthorised request is sent by a MEC Application
+    # Reference ETSI GS MEC 014 V1.1.1, clause 7.3.3.2
+    # Reference https://forge.etsi.org/gitlab/mec/gs014-ue-identity-api/blob/master/UEidentityAPI.yaml#/definitions/UeIdentityTagInfo
+
+    [Tags]    TP_MEC_SRV_UETAG_002_BR    TP_MEC_SRV_UETAG
+
+    Set Headers    {"Accept":"application/json"}
+    Set Headers    {"Content-Type":"application/json"}
+    Set Headers    {"Content-Type":"application/json"}
+    Set Headers    {"Authorization":"Basic YWxhZGRpbjpvcGVuc2VzYW1l"}
+    # Test Body: Register the tag user and check that the IUT has registered the tag user
+    Post    /exampleAPI/ui/v1/${APP_INSTANCE_ID}/ue_identity_tag_info    {"ueIdentityTags":[{"ueIdentityTag":"${UE_IDENTITY_TAG}","state":"INVALID_STATE"}]}
+    ${output}=    Output    response
+    Set Suite Variable    ${response}    ${output}
+    Check HTTP Response Status Code Is    400
+
+Precondition Failed error on invalid state
+    [Documentation]   TC_MEC_PLAT_UETAG_002_PF
+    # Check that the IUT responds with ProblemDetails on information an invalid URI
+    # Reference ETSI GS MEC 014 V1.1.1, clause 7.3.3.2
+    # Reference https://forge.etsi.org/gitlab/mec/gs014-ue-identity-api/blob/master/UEidentityAPI.yaml#/definitions/UeIdentityTagInfo
+
+    [Tags]    TP_MEC_SRV_UETAG_002_PF    TP_MEC_SRV_UETAG
+
+    Set Headers    {"Accept":"application/json"}
+    Set Headers    {"Content-Type":"application/json"}
+    Set Headers    {"Content-Type":"application/json"}
+    Set Headers    {"Authorization":"Basic YWxhZGRpbjpvcGVuc2VzYW1l"}
+    # Test Body: Register the tag user and check that the IUT has registered the tag user
+    Post    /exampleAPI/ui/v1/${APP_INSTANCE_ID}/ue_identity_tag_info    {"ueIdentityTags":[{"ueIdentityTag":"${UE_IDENTITY_TAG_INVALID_STATE}","state":"UNREGISTERED"}]}
+    ${output}=    Output    response
+    Set Suite Variable    ${response}    ${output}
+    Check HTTP Response Status Code Is    412
+    # TODO Check ProblemDetails
diff --git a/environment/variables.txt b/environment/variables.txt
index 1a5525860faa90ce92d8457538be27550c9f66a4..664bfc07853a34dbe0f0bbe2709335f766dfece6 100644
--- a/environment/variables.txt
+++ b/environment/variables.txt
@@ -1,8 +1,12 @@
 *** Variables ***
-${MEC-APP_SCHEMA}    http
-${MEC-APP_HOST}      192.168.0.17
-${MEC-APP_PORT}      8081
-${ZONE_ID}           zone01
-${APP_INSTANCE_ID}   appInst01
-${UE_IDENTITY_TAG}   UeTagA
-${response}          {}
+${MEC-APP_SCHEMA}                   http
+${MEC-APP_HOST}                     172.28.4.87
+#${MEC-APP_HOST}                     127.0.0.1
+#${MEC-APP_HOST}                     192.168.0.17
+${MEC-APP_PORT}                     8081
+${ZONE_ID}                          zone01
+${APP_INSTANCE_ID}                  appInst01
+${NON_EXISTENT_APP_INSTANCE_ID}     appInst99
+${UE_IDENTITY_TAG}                  UeTagA
+${UE_IDENTITY_TAG_INVALID_STATE}    UeTagC
+${response}                         {}
diff --git a/resources/GenericKeywords.robot b/resources/GenericKeywords.robot
index 6b3226b3a91745aae1d98f7a91a5857d78215c41..b609f8597ab1b04464cc3371410772a17d79e1e9 100644
--- a/resources/GenericKeywords.robot
+++ b/resources/GenericKeywords.robot
@@ -42,7 +42,7 @@ Should Be Present In Json List
 
 Check User Identity Tag state
     [Arguments]    ${ue_identity_tag}    ${state}
-    Log    Check ueIdentityTag state
+    Log    Check ueIdentityTag state ${state}
     Set Headers    {"Accept":"application/json"}
     Set Headers    {"Content-Type":"application/json"}
     Set Headers    {"Authorization":"Basic YWxhZGRpbjpvcGVuc2VzYW1l"}