I assume you have already done a proper Forum Search for your model number in case other people have already answered your question ?
If so and that didn't help then check out this thread: https://community.sling.com/message/10363#10363
Come back if it that doesn't help either.
Let's try a couple things and see where the issue lies.
First, let's make sure everything is all set with that IR emitter. Here are a couple articles you can follow to make sure the emitter is properly placed, and working:
Once the IR emitter is placed and you know it is working properly, you'll want to reconfigure the virtual remote control. Follow the process in this article:
While following that process, enter the same make/model cable box information (DCX3200M), and see if it works. If it doesn't, try some similar models (there should be one or two). Also, try entering in the name of your cable provider. For example, if you have Time Warner, you might find a Time Warner Cable universal remote. In all, I would try searching the model number, the manufacturer, and the cable provider. All of these searches might get you a working remote.
Hope this helps!
I'm running a Slingbox350 on a Motorola DCX3200M box. When using the Slingbox player on ANY device (tried tablets and PC), I cannot change the channel (or do anything, really) via the remote or the guide. I'm using the optional external IR emitter. I've attempted resetting the device.
When using my remote at home, it will change the channel on the slingbox app playing on my computer.