What am I doing wrong? Shinobi II

Hi everyone. I recently purchased the Shinobi II and am wondering if the calibration is off or if I have something set wrong. I've used it twice so far, both times on interviews where everything but my subject is barely lit. I'm shooting in s-cinetone which I've always trusted that what I was viewing on a monitor plugged into my fx3 was accurate. Something is up with how my Shinobi is setup because both times I had a beautifully exposed shot only to find out in post that I was considerably underexposed almost to the point where I wouldn't be able to salvage it in post. I'm really hoping that someone can help me figure this out.