People picker with FBA not showing names in most sites

I'm new to this SharePoint thing but I'm still supposed to fix a problem on our SharePoint 2010 site. Our team genius left not too long ago (No sarcasm intended) leaving us/me with a SharePoint site with a Forms Based Authentication implementation that isn't working all the way anymore. I'm told it once worked but I've never seen it.

Existing FBA users that are associated with the site(s) can still log in but new ones can't be given access because they aren't showing up in the People Picker. When I'm logged into the Central Administration site and on the Add Users page the People Picker there finds users in the ASPNet SQL Membership database. However, when I'm on one of the child sites those same user names don't show up.

Any suggestions?

I'm a puck