rewriterule with proxypass problem

hi i have this virtual hosy on my reverse proxy:
<VirtualHost *>
ServerName www.site.it
RewriteEngine on
RewriteCond %{QUERY_STRING} ^_pageid=91&_dad=paouts&_schema=PAOUTS$
RewriteRule ^/(.*) http://www\.sinte_new\.it/servlet/page [QSA]
ProxyPass / http://www.site.it/
ProxyPassReverse / http://www.site.it/
</VirtualHost>

i need both the rewrite and the proxypass and proxypass reverse, but
with this configuration it doesn't work the rewrite condition. if i
remove the porxypass and proxypass reverse all works fine...but as you
can immagine icannot remove the rewrite because i need it..
is there a way that all works fine?
thank you in advance