Wirelessly posted (Mozilla/5.0 (iPhone; U; CPU iPhone OS 3_1_2 like Mac OS X; en-us) AppleWebKit/528.18 (KHTML, like Gecko) Version/4.0 Mobile/7D11 Safari/528.16)
IIRC large blocks of OEM keys were "revoked" due to abuse/ keygen activity. This may be why some keys work and others don't...
Also IIRC the number you can call for activation can issue you a new product key if necessary.
B