Hmmm... That might be part of the problem. A null modem cable has the transmit and receive pins swapped along the length of the cable, so that the empeg's send connects to the PC's receive, etc. There are other pins changed, but those are the basic data ones.
If you just bought a straight cable (a default 9 pin serial), those pins are not switched and your empeg and computer will not be able to connect. You need the correct cable.
You might want to try
this out as well - it is the FAQ entry for setting up and testing serial connections. This is probably your best first step: upgrade to
2.0 final developer version for the Empeg Mark1.
Edit: linked to appropriate binary...