\frontmatter and \mainmatter does not work with pdflatex.

[R S Ananda Murthy]

Hello,
I am typesetting a book using Koma-Script Class in LyX. In this if I  
use \frontmatter and \mainmatter macros and then run pdflatex, then, I  
get error messages. But if I run ps2pdf it works.

In order to make it work with pdflatex I included
\renewcommand\pagemark{\arabic{page}}
in an ERT just before the starting of front matter and
\renewcommand\pagemark{\arabic{page}}
in ERT just before the starting of main matter. Then pdflatex does not  
cause any error messages. But I want the page number to be set to 1 at  
the beginning of main matter. To get this I modified the above  
mentioned command just before the starting of main matter to

\setcounter{page}{0}\renewcommand\pagemark{\arabic{page}}
But now pdflatex causes error messages where as ps2pdf does not. Can  
anybody help me in solving this problem. Preferably I want to use  
pdflatex to get pdf output.

Thanks for your help,
Anand