Cannot enable gitplugin

[anonymous]

I just installed Python-2.6.2, git-1.6.4.4, Trac-0.11.5 on a CentOS 5, and gitplugin-r6584

I have this lines on trac.oini

[components]
tracext.git.* = enabled

[git]
## let Trac cache meta-data via CachedRepository wrapper; default: false
#cached_repository = true

## disable automatic garbage collection for in-memory commit-tree cache; default: false
#persistent_cache = true

## length revision sha-sums should be tried to be abbreviated to (must be >= 4 and <= 40); default: 7
#shortrev_len = 6

## executable file name (optionally with path) of git binary; default: 'git'
git_bin = /usr/local/bin/git

[trac]
repository_dir = /home/git/repository.git
repository_type = git

and I stuill getting this message:

Warning: Can't synchronize with the repository (Unsupported version control system "git": Can't find an appropriate component, maybe the corresponding plugin was not enabled? ). Look in the Trac log for more information.

[anonymous]

probably the plugin can't be found by trac