It seems that you are having some issues with the SlingPlayer for Boxee box application since the DVR features do not work in a proper way.
As the first step, I recommend you to run the A/V source configuration one more time and make sure to select the DVR (which should be included on the supported devices list) option instead of cable box or satellite receiver.
Once you finish this configuration, make sure to launch the SlingPlayer for Boxee box application and test if it works in a proper way. If the issue persists, I encourage you to contact us through the Contact Sling Media options. We will provide you with the available support options depending on your Slingbox hardware, related applications and their activation date.
Hope this helps!