There's the solution for all Steam Community
Already found the Solution. To find the missing key, you go Start then Run and type regedit
Find the entry:
Underdome - Mad Moxxi's Underdome Riot Key:
The Zombie Island of Dr.Ned Key:
In "Steamkey" I find this key "Underdome - Mad Moxxi's Underdome Riot" and "The Zombie Island of Dr.Ned"
We fixed this case.
Finally you can re-activate the cd key