Dave Smith Instruments SYNTHESIZERS

I think I've isolated the problem. Let me know if anyone else has this trouble. It must be 
some strange quirk with the Evo because I also tried it with my Evo Desktop and the same 
thing happens,

-turn all oscillators off except Osc. 4, use any waveshape and turn up the volume.
-Open filter , and set VCA  amount to 100. 
-Everything else should be off. no noise, no delay, no LFO's or Mods. Everything else off.
-you should be getting only the sound of osc.4
-Now set distortion to 2 and sound disappears.

What the heck?