.htaccess - URL-Rewriting won't allow reg-ex as first paramater in address -

i using helicon ape in iis7 'mod rewrite' on windows server 2008.

very simple rule:

rewriterule ^([^\/]+) /index.php?page=$1 [l,nc] www.example.com/mypage 

this doesn't work, , have experienced on several sites. however, have reached problem transferring existing site (with above rule, worked in iis6, without helicon ape) new server, need work.

if add explicit parameter .htaccess before regular-expression, works fine:

rewriterule ^page/([^\/]+) /index.php?page=$1 [l,nc] www.example.com/page/mypage 

i don't understand why works , previous example doesn't?

the following redirects /mypage or /mypage/ /index.php?page=mypage

rewriterule ^([^/]+)/?$ /index.php?page=$1 [l,nc] 

you escaping / it's not required. (only \ does.)