One Test is not Rebuilding when trying run

When running my Tests one Test-Project where skipped (most of the time) I tried Test Explorer (and the Resharper Unit Test Session)

I found out that the Test-Project where also not building when Run Tests where selected. (by deleting the bin Folder and running the tests)

The Problem where that That in the Solution the Configuration were missing the checkbox Build

To solve it: RightClick on the Solution => Select "Configuration Manager" => check the check box Build (see Picture)