Can't understand how gitignore ignores the folders

I want to create repository for my Magento project. There are lots of folders and files in root directory and I change time to time only one folder: app/code/local/

Everything else I want to ignore. But.. can't. My .gitignore file:

*
!app/code/local/
!app/code/local/*

Then when I try to add folder to repo I get an error:

git add app/code/local/Mds/

The following paths are ignored by one of your .gitignore files:
app
Use -f if you really want to add them.
fatal: no files added

Can anyone please help with this?