Onr staff on page

I combined a Clarinet A and B flat part in one part by dragging the B flat part into the A part in Setup. Seems ok in Galley view (2 parts beneath each other), however in page view there’s only 1 staff per page. Btw: The Clarinet parts change per flow, not within one flow. It worked like a charme in other parts but I can’t seem to find any reason why this combined Clarinet part is off.
Any suggestions? Thanks!

Hold your horses, I’ve found the problem: The A-Clarinet bottom Music Frame Margin was aacidentally set to 75cm instead of 0,75cm!