I cannot install Monster Minis Extreme Off-Road Thread

I have Problems to install the game "Monster Minis Extreme Off-Road " .

OS: Ubuntu 12.04 64bit Mate Desktop

I installed the demo and all was fine and i played the demo. Now I purchased teh game in a bundle where I got a key.
Then I activated my key for the full version of this game. Now the full version was listed as "not installed".
But when I try to install it, I get: "There are no available releases for you to play" .

But when my son logged in on his computer iwth my desura account he had no problems to install the game!
My son has exactly the same hardware/software that I got and we both had the latest desura client.

Then I tried to copy the game from my son to my computer, but still no luck! Desure insists on "no installed"

So whats wrong here ?