Hey having troubles with the same display and library. Except that its just getting it to work on the MEGA. Tested it on the UNO with the code provided with the "Arduino 2.8 TFT Touch shield" which is the UTFT library. Triple checked the pins on the MEGA even probed then to make sure they weren't broken. I'm using the same shield that I used on UNO with the MEGA but it just doesn't like it. Also, I had to mod the HW_AVR.h to make sure the pins went where they were meant to.
I'm sure its something easy as I've never transferred a project from one to the other before.