1) Make sure that v_CurrentUser is getting a value that is exactly the same as your Helpdesk contact's NT ID. The Get Current User component, when configured correctly, would return domainname\username, which should match your Helpdesk contact's NT ID, but if the Get Current User isn't pulling back the domain name too, then the strings won't match. Use Altiris KB 43233 to ensure you're using the Get Current User component correctly.
2) I didn't see you mention how you referred to the Contact ID. You'll want to do something similar to the screenshot below.
Write back if you can't get it working, because I have gotten this working before. Just check the debugger's values at the end and make sure everything is matching up...it's probably something simple.