This plugin requires JomSocial v2.4.0 error

Iveth,
I'm assuming you mean you have JomSocial 3.0 installed, not 3.1, correct? Can you go to the Extensions -> Extension Manager -> Manage area and tell search for JomSocial and let me know what version it shows there? My guess is that it's like 3.0.1 Pro. Let me know what you see there and I'll do what I can to help. It seems like our installation check for too old of a version is getting tripped up by a 'Pro' in that column, but would like your feedback.

Thanks,
Alex