Gitlab on a Raspberry with Apache on subdirectory

I am using an raspberry pi(debian-wheezy) with Apache and now I wanted to add gitlab.

For testing I installed gitlab on a clean debian os and everything went well.
On the “live” system I installed gitlab as well, but I am stuck at setting gitlab as subdirectory/redirect.

I set my relative url at the gitlab.rb to /gitlab. I tried to set a system link to the gitlab root, but I get a not found Error.

Hope someone tried that already or has more experience to help me through that.