Izzaeon

Hi there, recently bought an appradio 2 and im using it with an iPhone 4S running iOS 6, The issue I have is 3/4 times I get into the car, plug in my phone and then start up the head unit, the music doesn't resume from where it left off, is there anything I can do to stop this from happening? Iv tried not closing the appradio app in the background on the iPhone but this doesn't work every time :/ Any help would be great, thanks