Can anyone help me work how to set the width of a report in the report designer to landscape?

I have worked out that the report should be:

Max width 27.94cm * 567(twips) = 15841.98 twips
Max height 21.59cm * 467 = 12241.53 twips

I have tried setting height and width to only 12000 width * 6000 height (twips) but the error I get is:

Report width is greater than page width.

Please help me stop tearing my hair out.