I might need to know a few more things to find out what is causing the issue. When you connect to the Slingbox, are you not able to use the remote to change the channel? If that is the case, here are a few articles that will help with your virtual remote if it is not working.
- Slingbox.com - I got a new set-top box, and I can't control my TV now
- Slingbox.com - IR Blaster/Remote Basics for older Slingbox models
- Slingbox.com - Advanced IR Emitter or Onscreen Remote Control Troubleshooting
Hope that helps!