I have deleted old versions and downloaded the newest trial. I added Silverfish to the custom deck but it will not select the play button. I am grateful to the developers working on a fix, so I am really just reporting the bug. I don't expect an immediate fix.
Please have a look at the HearthbuddyBeta GvG Release Thread. The Release version you downloaded is currently out of date (our sales system doesn't link the Betas), and we've just begun testing the new Beta to replace it.