5 panels or more on same row

I try to add 5 panels to the same row. In the below example I have four text panels with span 1. This panels fills up a third of my screen width. But when I add a fifth panel it is displayed on a row below the four panels, not besides them.

Is there a limit of 4 panels per row or am I missing some setting?

change the width (Span) of the 5h panel

Oh, I was sure I already tested that but apparently not. Your suggestion worked like a charm, thanks for the help!