More than likely it is not "shaking hands" with the system after you changed the system configuration by adding the RAM. The first place I would start is by resetting the SMC and PRAM. Instructions for doing that are [http://support.apple.com/kb/ht3964|here.] and [http://support.apple.com/kb/ht1379|here.] If this doesn't work we will work on getting you some directions. It should be very similar to the 13" which I know those instructions are here on ifixit.