CUDA 5.0 target problems in VS

Hello, I am trying to build a very simple code in VS13. Since I have both CUDA 6 and 5 installed I had to change the build customization settings and add CUDA 5 target manually (I need it for optix) while the CUDA 6 already appeared. Once I selected 5, I linked cudart.lib and changed the platform to VS10 but got this error:

C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v5.0\extras\visual_studio_integration\MSBuildExtensions\CUDA 5.0.targets(535,13): error MSB4064: The “Name” parameter is not supported by the “SetEnvironmentVariable” task. Verify the parameter exists on the task, and it is a settable public instance property.

What am I doing wrong?

Also, before I got this error I also got a COFF error which disappears if i disable incremental linking.
If I compile with CUDA 6, without incremental linking, it works.