How to fix the scenario of No tests to execute via MSTEST in TFS build log?

On June 13, 2012, I wrote a post about How to fix the scenario of No tests to execute via MSTEST in TFS Build 2010?  But I forgot to mention another important thing. You might find this post helpful to you if you have the same issue.

On June 12, 2012, I created a test project that contains unit tests and web tests.  In Visual Studio 2010, I created a new test list called BVT and put all of the tests in BVT and then I checked in the code to TFS source control. After I kicked off a new build in TFS, the build succeeded, but all of the tests in BVT never got executed in the build log (No Tests to execute.)

I logged in to the build server and opened the .sln file of my test project. The interesting part was that all of the tests in BVT were not enabled. I needed to manually click refresh in the test list editor to make them enabled. How did I make those tests enabled in BVT Test List without clicking refresh manually? 

After long investigation , I must check in the bin folder and can’t check in the obj folder. This is  very important!  If I put more tests in BVT, I need to check in bin folder again to make those tests changed. 

After I kicked off a new build again, all tests passed in the build log. After logging to the build server again, all tests were enabled in BVT Test List as well.