[sgroup] Partial SMT Control

Hi, I'm having trouble understanding what this parameter does. There's a SMT Velocity Control I know the Velocity is controlled by the Note On Data 3 byte, but when the SMT Vel Control is set to Off, and the the Patch Has it's SMT Control Selection set to Ctrl Change, and the Ctrl Sel is set to #30, shouldn't the CC#30 control the velocity of the Resulting SMT / Note Ons? So the Value of CC#30 controls the velocity and not the Note Ons? It doesn't seem to be working for me... and this is testing under the performance tab. Am I missing something here? Cheers, Adrian