iphone 3gs wont connect to itunes

i got an old iphone 3gs for free and all i had to do was clear the info off it, but it was still running ios 4.3 and i didnt want to lose its speed so i just reset it from settings. And when it finished i got the "activation lock" and it told me to connect to itunes. I put in my sim card and plugged it in but itunes isnt doing anything at all, my iphone isnt making any indecations that its plugged in. Ive reinstalled itunes, tryed 2 other usb cables, and all my other idevices work just fine, just this iphone 3gs. The iphone charges when plugged into a wall, but not in any other computer, ive tried 2 other computers, in restore and DFU mode and still nothing, any help?