Synthmaster Vocoder isn't working for me. Help?

[smoothassilk]

Hello.
I'm using Synthmaster 2.6 with reaper and I'd like to be able to use the vocoder.

I have two tracks:
One has a vocal sample on it, with the send to the master bus removed so I can't hear it.

The other has synthmaster 2.6 effect on it.

I've added a send from the vocal track to the synthmaster track, turned on the vocoder and turned the vocoder mix up to the max. I can see the modulator spectrum just fine, and I can hear the vocal modulating itself. So far, so good...

Ok, now instead of the vocal modulating itself, I want to get it to modulate a stack of saw waves, so I change osc. 1 from AudioIn to basic sawtooth.

Now all I can hear is a saw at the same pitch as the modulator. If I feed MIDI into the effect, I can get a normal sawtooth at whatever pitch I want, but all the time I can hear this other sawtooth at the same pitch as the modulator.

Is this a bug, or am I doing something wrong?

All help appreciated.