I encountered the same problem and dug into the plugins files for a bit to try and solve it. After some sifting through the code I found the solution.
In the plugin directory ‘wordpress-mobile-pack’ you’ll find the directory ‘plugins’, in that directory there’s a folder called ‘wpmp_switcher’ where all the sweet switching goodness is going on.
In the file ‘lite_detection.php’ there are a few functions that look at the browser User Agent for keywords and uses that to decide whether a browser is a mobile agent or not.
Under the second function ‘lite_detection_ua_contains()’ you’ll find a list of device names like android, blackberry, ipod etc. I added the name ‘ipad’ in the same fashion and voila, it worked!
One of the reasons I think this was broken is because Apple explicitely added ‘ipad’ to their user agent code instead of keeping it the same as the iPhone.
Hope that helps, happy hacking!