Does anybody know if these leads are interchangeable between ipod(touch) and ipad(3). The reason I ask is that tried to charge my ipad whilst at work but someone has borrowed my charge lead, so I went through mt bag and found the charge lead from my pod touch. When plugged into the pad it says it is charging for about half a second then say not charging, just like when you plug into an unregistered PC. Is their really any difference between leads.