Sand-blasting cabinets?

The tips are ceramic. The siphon tube is not clogged. Air comes out of the siphon tube & the tip. There is nothing clogged. My understanding is that the air pressure rushing over the siphon tube should create suction which picks up the media & "blasts" it out the tip. My gun sends air out the tip & out the siphon tube. I will try taking the tip off & changing it. I may go to Northern tool & get a new gun & try it before I give up, put everything back in the box & throw it through the window at HF.