Converted .NET 3.5 project to 4.0, But asking for migration everytime when open the solution

Hello,

I've converted a VB web project from .nET 3.5 to 4.0 version and checked in to the TFS, But when i try to get the latest project on other user's machine, It is showing the conversion wizard even though i've converted it to 4.0 and checked in. I've even checked TargetFrameWorkVersion in .vbproject file. Can any one please let me know how to check whether the solution is really converted to 4.0 or not?

Thanks,