Strobe from Effects Engine?

I am working with IntellaBeams and Studio Commands. Trying to build an fanned-offset strobe effect so that each of the fixtures is has the strobe shutter open at a different time. When I try to access the strobe parameter in the effects engine I am unable to do so. What am I doing wrong and is there any other way to achieve this?

PS. I don't want to fan the strobe rate or flash the intensity flag (as in the chaser effect) because it doesn't move quick enough for a strobe effect.
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