Attachment thumbnail preview and light box not working
 

I just realized i had this functionality on my board. i always though it was a mod i saw on other peeps boards. but its not working on my site. what could be the issue. i turned off my hook system uploaded a pic just to verify that there wasn't a conflicting mod. i also made a fresh new default theme to be sure there weren't any template edits causing an issue.

what are some things i can look into?

thanks in advance