Just plugged an iPhone 4s into my xcarlink and it charged ok. Then swapped back to my iphone4 which now no longer charges! Tried another iPhone 4 and that doesn't charge either. Switched back to the 4s and that still charges ! Music still goes through the xcarlink ok from the phones. Has anyone experienced this at all? I've asked xcarlink support but wondered whether anyone else has experienced this and knows a fix?