TFS 2012 build exclude some project from compilation process

I have some strange behavior in my automatic build. When I open solution properties in build workspace I find that there is one project not checked in configuration to build, and my build fails. When I open this solution from TFS source control, this project is checked and build in VS pass successfully. Does anyone have an idea of what can exclude the project from solution configuration in build process? Could there be any other reason for this problem?

i have saw this post it my be similar but did solve my problem 

http://social.msdn.microsoft.com/Forums/vstudio/en-US/eef975d2-c2ad-4d5b-80d8-0f4f3a9ce059/how-to-exclude-project-from-build

help will be appreciate

shlomi