Log off Battle.net restart the browser and log back in. If it persists call blizzard support...
Australia Account & Billing: 1-800-041-378
New Zealand Account & Billing: 0800-452-520 (7 A.M. - 5 P.M. NZST)
(Hours: 7 a.m. - 8 p.m. Pacific Time, seven days a week)
However it may be a used key if you brought it from somewhere that wasn't the Blizzard store.
4.7 years ago