when you say the rpm's do not change in the different gears, are you saying that when its at dead stop, you can shift it from neutral or park into 1,2, or 3 and all three drop the rpms by the same amount?
As I understand these trans, you should be able to shift into first (all the way down) and the rpm's should drop a bit as the trans initially engages just like a regular auto trans. This would happen with any auto trans when shifted from neutral or park into a gear (any gear). It's not under load so the rpm's are higher. Once in a gear (any gear), it's under load and will drop a bit. It should drop the same amount if you dropped it into 2 from a dead stop instead of 1. Of course, you would then be starting off in 2 when you should start in 1 and work your way up.
I hope I understood your question okay.