USB Charger Works With BF's iTouch But Not With Mine?!

Hello! My apologies for this being a bit long even though the problem is pretty straight-forward:

Both my boyfriend and myself have the iPod Touch 4 G. I bought mine a few months ago and bought his for a Valentine's Day present for him on Feb 14th of this year. So about a week and a half ago or so. So, the problem is with charging them. I have a Powerline dual usb wall/car charger that's been working fine for about three years. It will charge my tablet PC and it will also charge my boyfriend's iTouch. It will not, however, charge my iTouch. I can charge my iTouch through the computer or through our wifi router's usb port but as soon as I plug it into our wall charger: zip. If I plug it into the wall charger while the iTouch is turned completely off the iTouch will boot up instantly after being connected to the wall charger but it won't charge at all. Anyone have any suggestions?

Maybe I will just have to get a new wall charger for my iTouch. I really need one as I am going to be staying with my grandmother for the month of March and she has no computer or anything for me to charge my devices on other than the wall socket. It's just odd that my wall charger will charge my boyfriend's iTouch and mine will boot up when connected to it, but it won't charge it at all. Thank you for reading this and hopefully providing me with a workable solution. Oh, yeah, forgot to mention; I reset and restored my iTouch and tried it again. No luck. At least it's charging via other means; computer/wifi router, but I'd like to find out why the wall charger is only charging one of our iTouches.

I have tried resetting the device and I have also tried restoring it to factory settings and starting from scratch. I have tried other usb iPod usb cord/plugs, (we have three; one's mine, one's for my boyfriend's iTouch and one's left over from an upgraded iPod), and I have tried plugging the charger into different wall sockets. Like I said; it will charge the boyfriend's iPod fine and my iPod will boot up from complete shut down when plugged into the wall charger but it won't start charging.

Thanks!

~Ami E. Bowen