error MSB4019: "Microsoft.WebApplication.targets" was not found

Hello,

i tried to build our Webproject with the TFS 2010, i created a build definition and started the build. At the end i get an error:



error MSB4019: The imported project "C:\Program Files (x86)\MSBuild\Microsoft\VisualStudio\v10.0\WebApplications\Microsoft.WebApplication.targets" was not found. Confirm that the path in the <Import> declaration is correct, and that the file exists on disk.



That is the one error in the BuildLog.txt



Has someone a solution??