I want to control a motion sequence from the MS amplitude and shape knobs (there's no way to assign knobs to a motion sequence so far as I know). But nothing happens. Local Control is on; other knobs such as Filter Cutoff work; the display shows Part x Amplitude changing; I've tried various initial settings of Amplitude in the Part's Motion Sequence Edit screen, as I know the knob controls the offset value... but it's not affecting it. What have I missed?