Region locked on humble bundle?

You must have been gone quite a while then. Publishers started doing region-specific keys on Humble (plus Bundle Stars) over a year ago. Not everyone, but that particular thing is the multiplayer demo for Blops3, and it was locked around the usual server regions. Your key only works in Europe, but since there is no EU region here (despite popular demand), you can choose a German or a Pole to carry the blight of having anything Call of Duty past CoD4 in their library.
Or just keep rerolling until you find a European. Since you posted it as level 0 public, it may take a while—usually the overwhelming, vast majority of the entries on those are from the trio of RU-CIS, South America, and SEA+China.

You should verify it with Humble's support if the purchase screen says nothing on it.

Some publishers do that for some reason. 2k did the same with Xcom 2.

it's region locked, i had given permission to remove that title i won before due to same issue.

Thanks for the info guys. I'll make sure to give the person a different key.