Gitblit blockpush hook not called

I just edited the blockpush.groovy script in the groovy folder of the gitblit installation. I simply "return false;" in order to check if the script gets called. Also, in the test script, there is nothing written in the log file

Indicate we have started the script
logger.info("blockpush hook triggered by ${user.username} for ${repository.name}: checking ${commands.size} commands")

/*
 * Example rejection of pushes to the master branch of example.git
 */

def file1 = new File('C:\\workspace\\test.txt')
file1.write 'Working with files the Groovy way is easy.\n'

return false

What am I doing wrong? I am commiting and afterwards pushing

I was not paying attention that this code was the important part

 for (ReceiveCommand command : commands) {
        def updatedRef = command.refName
        if (updatedRef.equals('refs/heads/master')) {
            // to reject a command set it's result to anything other than Result.NOT_ATTEMPTED
            command.setResult(Result.REJECTED_OTHER_REASON, "You are not permitted to write to ${repository.name}:${updatedRef}")
            blocked = true
        }
    }

You need to configure your repository to use the blockpush hook script.