Does not charge on AC Power, only on iMac

I have been trying to fix a New iPAD with GSM (iPAD 3 4G) for 2 days, so this is my last resort (after tonight I try to update to IOS7).

- The iPAD chargers perfectly on my iMAC.

- Tried 2 chargers 2.1A both not working. Went to the Apple store bought a 2.4 12Watt one + original Apple Cable just to make sure, no charge

- Changed the 30 pin connector for a new one, same story.

- Tried to downgrade to another IOS version but keep getting the error "device not suited". Hoever, sure I got the correct ROM. Followed all advises like changed the HOSTS file to no resolve.

- Tried to jailbrake to an older version, but seems no 6.1.3 jailbreak yet for downgrade.

- Will try IOS 7 tonight see if that can solve it.

Thought about changing the battery, however now its 100% and working well. Seems that cant be the issue. Still got the screen of the iPAD so could try it. I read quite a few people experienced this issue after updates but I dont read any solution other then people suggesting we use a wrong charger, which I am sure I am not:). its a 4.2 12 Watt bought in Apple store with 30 pin Apple original cable, again.