My daughters ipod touch says it is not charging but it is, however it is not recognised by itunes

My daughters ipod touch 4th gen was working fine but today when she plugged it in to various data cables and devices it didn't beep or bring up the charging symbol. It was not recognised by the pc and itunes either. However i left it plugged in to the pc and it is charging. Cable is fine on my iphone so its not that. I'm worried its going to crash altogether and i cant back it up because it wont link to itunes. But how can it charge without saying its charging? Have tried rebooting both ipod and pc.

Anyone any ideas?

I did have a fairly similar thing with my iphone which turned out to be the data port which had erroded due to damp, not been wet just condensation etc i think, any one had any similar thing happen?

Thankls

Gaz