Approx 1/3 of lower portion of picture is dark

Using a 16-24 wide angle lens,9.25" dome and a pair of ikelite 161's when I move the camera close to the subject, I mean the dome is 1" away, the lower portion of the picture is dark. A distinct line where the light from the flash can be seen, then horizontally, 1/2, 1/3, 2/3, or 1/4 of the lower portion of the picture is dark, as thought the light of the strobe did not make it. I've moved the strobes all around and can not figure out why. I cannot upload a picture at this time, so just imaging the lower portion of the picture is dark. A distinct horizontal line.. Ideas why and what I need to do to correct this?

Either you have the strobe aimed improperly or your system is not in sync.

Have you been using the aiming light to make sure you are aimed right?

The dome is blocking the light/strobe so move it forward slowly or re-position your light source! Be careful not to move them too far forward or you'll get a bad reflection off your dome! Sync is not the problem it used to be with digital cameras compared to film....