iis 5.0 and proxy server

Hi i have iis 5.0 on a windows 2000 machine. my proxy server is nt 4 proxy server 2.0 i cant seem to publish anything on iis 5.0 yet my old website which was 4 was ablt to publish it. am i missing anything? do i need to install a service pack? what needs to be done?

thanks
Vince