That's a weird responce from URC.
I didn't know usb cables have configurations???????
Software yes, but usb cables?
But it's possible you got a cable without all of the pins.
Usually usb to serial adaptor cables can cause problems if you have the wrong kind.
But usb cables are pretty much standard, as long as you have the mini device plug on one end for your mx-3000.
You could always use a cellphone usb cable, as I do too.
I use a COMMON motorola usb cable with the mini device plug for downloading to my cell phone AND mx-950, etc., with no problems.

The mx-3000 and mx-950 also use active sync to communicate with their mini operating systems, as do some MS smartphones(I have a cingular 8525).
So active sync comunications with it should be standard too.
When active sync connects with the mx-950, I don't sync it, since there is nothing to sync(i.e. folders and such, as are on my cell phone).
But it develops a partnership with the mx-950 so I can communicate with it.
Sometimes it takes a couple of replugings for active sync to startup and connect, but that's about it for me.
I know when I have a good connection when my computer dings and the mx-950 makes a weird sound(hard to describe, but when there is a good connection. I know by the sounds of the computer and my mx-950, your mx-3000 may do the same).
Active sync also flashes and wants to develop a new partnership(I ignore this, since it's not nessary for the URC remote).
As long as active sync shows it's connected, that is all that is nessary.

Hope that helps some.

Good luck.