Error message when trying to post a classified ad

Hi I installed the classifieds plugin on my site which has buddypress and multisite, to see what it was like before tri. When I try to create the ad before trialling it on a clients website.

When I try to create a new ad I get this error message:

Warning: Invalid argument supplied for foreach() in /var/sites/s/ on line 24

I also cant view the classified main page listing classifieds etc, what would the url be for that?, many thanks