So the contacts of the cable (dock connection side) were wet and i didn't know that. First, i plugged in my ipod touch 4g like always, it was ok. And after few hours using it, i plugged it in to charge again, and then in started to charge and stop rapidly, with the "charging is not supported with this accessory" message. I unplugged the cable. and looked at the cable's dock connection's contacts. There were places, where it looks like the cable is burned. So now i don't have a spare cable, to try it on and I'm really scared, because it could damage my ipod's internal parts. My ipod is still working fine, so i dont know if it's really damaged. Could have the contacts of the ipod burned? Thanks.