Hi, I've just bought a Macbook pro and I'm trying to connect it with my old Imac 2009. I've purchased a thunderbolt cable and connected one side via thunderbolt port on the MBP and the other side in the mini display port of the Imac. Unfortunately when I press CMD+F2 on the imac to use it only as a display screen, nothing happens. Please can you help me sort this issue. Thanks.