One question that I have been asked multiple times is -

When I’m trying to bind the user scenario with the test cases through Microsoft Test Manager, I see the link type “Tests” but this is not letting me associate the user scenario to the test case. What am I missing here?

The error shows like below in MTM (and similar issue is there in VS too) -

NotAbleToAddLink

The reason for this is that with TFS 2010, the Work Item Tracking has a notion of Work Item Category.  There are type of links that are allowed only for certain categories.  For example, in the above case the “Tests” link is allowed only to an item belonging to Microsoft.RequirementCategory. (Similarly a “Tested By” link is allowed only to an item belonging to Microsoft.TestCaseCategory.)

In the above case, user is getting the error because the item she is trying to associate does not below the the Requirement category.  The reason for that in this case was that user had created their own custom work item type. The fix is to add this custom work item type to the appropriate category.  To do so, refer this blog by Rubel in our team.