Please help me with git4idea integration

Hi all,

I am working to build my first Intellij plugin, but I encountered a problem. My apologizes if my question is already replied or is stupid.

I am trying to get Git branch name and for this I am did something like:

Git git = new GitImpl();
GitLineHandler gitLineHandler = new GitLineHandler(project, virtualFile, GitCommand.BRANCH;);
GitCommandResult gitCommandResult = git.runRemoteCommand(new Computable.PredefinedValueComputable(gitLineHandler));

Unfortunately, I receive an error:
java.lang.ClassCastException: git4idea.config.GitVcsApplicationSettings cannot be cast to git4idea.config.GitVcsApplicationSettings
    at git4idea.config.GitVcsApplicationSettings.getInstance(GitVcsApplicationSettings.java:49)
    at git4idea.commands.GitHandler.<init>(GitHandler.java:127)
    at git4idea.commands.GitHandler.<init>(GitHandler.java:153)
    at git4idea.commands.GitTextHandler.<init>(GitTextHandler.java:47)
    at git4idea.commands.GitLineHandler.<init>(GitLineHandler.java:52)

Intellij version: 14.1.3 Community
OS: Rhel 5
In order to get git4idea.jar, I copied it from the location where I have Intellij Community sources/plugins/git4idea/lib/*.jar in the location where I have installed Intellij/plugins/git4idea/lib/*

Any suggestion is more than welcome!

Thanks in advance!