Virtualmin, Git and Auto Deploy


I set up virtualmin on CentOS with Git Repositories. Then, i read many tutorials how to deploy to public/html but i cant do it work (without any error/message). I think that i didnt set right permissions.

In detail:
domain owner (domain/public_html) : gitd / gitd
git (domain/public_html/git): apache / gitd git
user who push: chris / gitd

My post-receive file has the following code:

GIT_WORK_TREE=/home/gitd/public_html git checkout -f
When i run it via root it works! But when i push changes through git the public_html folder does not update it (only git).

Any ideas please???