I recently got a macbook air 11" and wanted to use my 27 inch imac as secondary display. I connected the thunderbolt cable between the two and hit cmd + f2 on the imac. Both screens flashed (light) blue as if it was going to work. But the Imac just came back with its own screen, and the keyboard and trackpad became unresponsive. I could remote login to the imac via the macbook to turn it off. Does anyone know a fix for these problems? Am I doing it wrong?