I understand that you are having some issues with the SlingPlayer for iPad application, since you are not able to get all of the channels on the Program Guide.
As the first step, I recommend you uninstall and reinstall the SlingPlayer for iPad application. If you do not know how to, feel free to check this link:
Once you reinstall this application, I encourage you to run the AV source configuration one more time and make sure to select the specific cable service provider (according to the Zip Code of the Slingbox location). This way, you should be able to get the right channel line up.
Let us know how it works for you.