Upload Button doesn't work

Hey guys,
It seems that the attach button in my self created theme doesn’t work. I work with the latest Wordpress and Buddypress version. It works perfectly with the standard theme but not with my own. Also I am unable to create photo galleries or upload photos from the user profile. I think it’s a JavaScript error but i can’t find out what causes it.
Do I have to implement something or change some code?
Thank you for your help.

Yes, there may be some javascript error. Please check console and resolve if there is any js error.