This accessory may not be supported iPhone 4
I have an iPhone 4 and I have a usb for it which I use to charge it up with on my laptop. Whenever I plug it in it will charge for like 2 seconds and then the message "This accessory may not be supported" appears on my iPhone and stops charging. I have to wiggle the usb wire around a few times before it starts charging again. Do I need a new charger?