Windows Store Apps WACK failed : Performance suspend

Hi, I am trying to submit my app to Windows store, but fail certification. I created a new Unity project, with 1 scene in it that is totally empty (camera only).

Configurations:

1. Windows 8.1 on Parallels (mac).

2. Unity pro, version 4.3.4f1.

3. Windows SDK 8.0.

4. Windows App Certification Kit 3.1.

   Error message:

Performance suspend Error Found: The performance suspend test collected the following results: Application Error: Application Suspend was not detected for application App. This could be because your application failed to suspend correctly. Please consider re-running the test avoid interacting with the application while tests are running.

Any suggestions...?

Thanks!