# LyX headers and footers don't span page [closed]

I'm creating a document using LyX with various packages in the preamble. I'm setting different fonts, setting colours and I have multicols working. The problem is that for some reason, the headers and footers only span about three quarters of the page (or around the centre point of the second column).

Is there anything in multicols which might be causing this?

My mimimised preamble is below. It does it without any text. I'm sure that one of those parameters is mucking it up, but I'm not sure which one.

\usepackage{multicol}
\setlength{\intextsep}{0cm plus1cm minus1cm}
\setlength{\textwidth}{39pc}
\setlength{\textheight}{54pc}
\setlength{\parindent}{1em}
\setlength{\parskip}{0pt plus 1pt}
\setlength{\oddsidemargin}{0pc}
\setlength{\marginparwidth}{0pc}
\setlength{\topmargin}{-2.5pc}