Blank screen on easy discuss view

I installed easy discuss 3.1.8872 on J1.5 and always get a blank screen when i access the easy discuss category view. no errors etc on reporting at maximum. The Backend works fine.
I'would like to try an older version but it says "We are sorry, but the extension is invalid. Please contact support@stackideas.com" on your site when i try to download one. Is there a way to download them?

Best Regards