It seems that you are having some issues with the connection to your Slingbox PRO HD since the signal is not good enough.
In this case, I recommend you to test the connection speed one more time when at the Slingbox location. Among other options, you can test it through www.speedtest.net. Keep in mind that the most important one is the upload speed, that should be at least above 3Mbps. If you get something below to this, the signal will not be good enough.