Since there is no bio load in your tank, there isnt any fish-made waste for the skimmer to remove. Without waste in the tank, there is nothing to foam up. Its like putting bubble bath in a tub, the spraying water might make some small bubbles, but it wont foam until the soap is added.
OK, so we know you have nice clean water and no waste, but do a quick google on SeaClone skimmers. You will likely not find one positive post about them. They are so awesomely bad that they should be withdrawn from market. If you can either return it or sell it, you will be much happier in the long run, and your tank will be healthier. SeaClones just dont work.