could be the dash (that is where 1 of the 'termination resisters" in the can bus is actually installed, so if the dash was wacked out, you would also have no communication between the ecm, vcm and dash due to a can knock out), but as a general rule, when it is the dash, either you get no dash at all, or the trans won't engage but the engine will run.
I would say it was worth trying a known good dash, if you have one.
actually though, if the cat tech did not get any communication at all, it is most likely IS the power to the VCM or the VCM itself, since (also, as I understand it) the cat program communicates through the VCM to 'talk' to the dash or the ECM.