3 things I can think of:
1. Make sure your hard disk is set as bootable and has
a bootable OS.
2. Make sure you have taken the Compact Flash card out, it
will prevent you from booting your disk.
3. I have had problems with GCT's that came with the
44pin header already installed in that there is usually
one pin that is missing out of the 44. I take a piece
of 1/4watt resistor lead, solder it to the pad where the
pin is missing, and with a pair of needle nose pliers,
bend it over, up and straight so it is in line with the other
pins. Then cut it flush in length with the others. Carefully
re-attach cable and see if that helped...