Jon,
Did you try programming device code 0775 on the cable button. This code is definitely in the 15-1994, so if you get one long blink rather than two short ones, you are doing something wrong.
But, if the 0775 code is accepted but still does nothing to control your dish, then you might be out of luck.
Here's the deal with the 15-1925 remote. It has the internal modem that you mentioned, which is great because you can always call and get new device codes added, and it has an RF extender, so you can use it from another room to control your system, but it is an old-fashioned style remote, which means it does not have menu arrow buttons. Plus, it does not have learning abilty, so you will need to find device codes for everything, but you can use advanced codes and key moves.
It has the four main transport keys (play, stop, rew and ffwd) arranged in a kinda circle, so you could use these for the menu arrows if you don't need transport keys.
Hope that helps,
Rob.
http://www.hifi-remote.com