Generally speaking, the Pronto needs to be connected to the first available COM port. I can’t recall whether a COM port not existing is good enough for it to try the next, but if there’s a COM1 and the remote’s connected to COM2, then COM1 has to be busy or the connection will fail. There is no configuration possible, it’s automatic.

It will also have to be in the standard COM1 through 4 range, not COM12 or something.

[Link: remotecentral.com]

Also, make sure you’re using a proper Pronto cable and not one with reverse wiring. To verify that everything’s good between the remote and your PC, you can use a terminal program to connect to the remote and see if you get the boot up text. Instructions here:

[Link: remotecentral.com]