Re: I can't create cards - button is unactive

H tokens are specific to only Common cards. If the button is inactive, I would bet it means that either 

a) you are out of H tokens to use and you need to earn more.

or more likely...

b) you have completed the Common set, which means you no longer acquire or use H-Tokens. Once you have completed the common set, the only cards you can "CRAFT" will required Sparks, not H-Tokens. The Spark icon is the lightning bolt in blue

I haven't used H tokens since last April or May, and even if I remembered what it looked like then - i'm sure it's changed since