Mongoyii And Connection Using Openshift

I have successfully uploaded the yii template application to OpenShift and added the MongoDB (version 2.2) service to my app. However I don't seem to be able to make the connection.

OpenShift give me the following information (slightly changed here for security):

MongoDB 2.2 database added.  Please make note of these credentials:
   Root User:     admin
   Root Password: 3Uhu78sikjat
   Database Name: newmdb
Connection URL: mongodb://$OPENSHIFT_MONGODB_DB_HOST:$OPENSHIFT_MONGODB_DB_PORT/

This is what I have added to the main.php file

'mongodb' => array(
			'class' => 'EMongoClient',
			'server' => 'mongodb://admin:3Uhu78sikjat@$OPENSHIFT_MONGODB_DB_HOST:$OPENSHIFT_MONGODB_DB_PORT/',
			'db' => 'newmdb'
		),

I have been able to get this working locally but cannot connect once uploaded to the host service. Any ideas what I'm doing wrong? This is the message i get from the server...

Failed to connect to: $OPENSHIFT_MONGODB_DB_HOST:0: No such file or directory