Unable to restore iPhone 3G 1015 error

I am trying to restore a new iPhone 3G Unlocked bought from Valid Reseller with Invoice

It always says 1015 error cannot restore.

I upgraded iTunes, restarted computer, Downloaded the latest IPSW Nothing works [ iPhone2,1_4.3.3_8J2_Restore. ipsw ]

I have read all the forums and tried all the suggestions.

Any help greatly appreciated.