New skimmers usually have a break-in period where they are very tempermental for a week or two. Some will produce tons of skimmate, others hardly any. Be patient and your skimmate production will even out.
Start with the bottom of the collection tube just below the water level in the skimmer. Then raise it 1/4" every day until you are getting a thick, greenish-brown skimmate.
Be patient, you got a good skimmer and it will take a little time.