Since DCS World is avaible on Steam, Steam granted their customers another new serial number/different from the original products serialnumber to the DCS A-10C for your Steam account for use in DCS WORLD on Steam (DLC CD-Key for the A-10C). You might have added the serial number to your non Steam Version of the game in the past ( I had bought all 4 A-10C modules for my 4 playeraccounts I do own via Steam before DCS-World was avaible on Steam/thats why I know about this issue)
Here an important information for the players who purchased the A-10C via Steam before DCS WORLD was released on Steam.
