How to run opencvplugin of kurento media server in my nodejs server

I have followed the tutorial on the kurento site about creating custom opencv modules. I managed to create it and add it to kurento media server. As an example I used kurento-crowddetector code. I have changed the following lines. I used the sample opencv module from kurento site and didn't modified anything. Server starts with no errors. Only problem is that remote video isn't visible, the circle is spinning. No errors is occured in the console. It seems that it missing some small part of the code but don't know which. Did anyone knows how to fix this?

kurento.register('kurento-module-opencvpluginsample');

function createMediaElements(pipeline, ws, callback) {
pipeline.create('WebRtcEndpoint', function(error, webRtcEndpoint) {
    if (error) {
        return callback(error);
    }

    pipeline.create('opencvpluginsample.OpencvPluginSample', function(error, filter) {
        if (error) {
            return callback(error);
        }
        return callback(null, webRtcEndpoint, filter);
    });
});

}

via M.Zemo