A project %0 you are trying to add contains items which are in the same folders as projects that are already under source ...

A project %0 you are trying to add contains items which are in the same folders as projects that are already under source control. Because the source controlled projects do not share the same source control binding, they cannot be added to source control. To resolve this issue move this project's items into their own folders, or place all overlapping projects into the same source control binding.