Collectible Card Game Headquarters

Hello, I am getting the following error message in the attachment whenever I try to click the 'Unlock Sets' button above 'Travel'. I am currently up to the hard mode opponents and am still stuck with my opening sets of Innestrad and Dark Ascension, so any advice would be appreciated.

Also sorry, I realize I'm using an older version of Forge (I use Snow Leopard and this is the last version that works); apologies if this is irrelevant to your current objectives!!