Ok, I had this same issue on the Iphone 4 where the remote kepad on the mobile app would not allow me to enter the "." or "-", e.g., channel "4.1 or 4-1". Somehow it got fixed, but I now have the same issue with the Ipad. When I try to change channels on the mobile app by using the keypad, the "." is greyed out. How can this be fixed. I have a Directv HD DVR and the setup is correct.
In this case, we recommend you to rerun the TV source configuration using the SlingPlayer software on your computer. Just make sure to select the right make and model for the supported TV source. If the issue persists, we encourage you to post your results and please include the specific model for your TV source (cable box, DVR or satellite receiver).