theme not working after activating multisite

at I have set up a wordpress multisite, so that I can have users sign up and have an option like this:

I have done everything in terms of setting it up, the only thing i did differently was that i used sub directories and not sub domains. everything seems to work fine until i get to creating a new site and selecting it’s theme. it works when i create a new site, but the theme is set to twenty eleven. when i change it to my custom theme, it breaks the new site. giving me this error message:

it only gives me the error message when i have my custom theme installed. it’s a buddypress multisite i’m trying to create. the theme is specifically designed for buddypress…i’m not sure if that makes any difference or not. but i can’t seem to figure it out regardless…