Span grid across the whole page

Hi all,

I have a WebPortalPage with only a grid on it.
Unfortunately only the first 5 entries are shown although there is a lot more space is available.
I have tried changing the size of the only row to automatic and to 100%.
I have tried adding rows with and without spanning the grid accross them.
Nothing worked for me.

Any hints?

Regards
Klemens