debug is really only there to make sure the ecu is talking right. you are basicly sending break's to the ecu and see if it responds. you should plug it in and then say connect and it should give you the ecu part number. if you dont get that...then probably dont have calumsult pointing to the right com port that your adapter is using.
and honestly there are better programs. that program he wrote years and years ago as a quick and dirty thing to get a few things going. pay for nissandatascan, its a lot nicer of a program honestly. calum is a hardware guy not a software guy...despite the fact hes now a programer in his day job...