IIRF ProxyPass ignored

I'm using IIRF, IIS 6.0, W2k3.

I'm trying to use ProxyPass, as follows:

RewriteLog  c:\temp\iirfLog.log
RewriteLogLevel 3
RewriteFilterPriority HIGH
ProxyPass ^/foo/(.*)$ http://www.example.com/$1 [I]

but it nev开发者_StackOverflower works. The IIRF log shows:

Wed Jun 30 13:19:54 -  6120 - ReadConfig: setting LogLevel to 3
Wed Jun 30 13:19:54 -  6120 - ReadConfig: line 13: RewriteFilterPriority HIGH
Wed Jun 30 13:19:54 -  6120 - ReadConfig: Filter Priority is now: HIGH (0x80000)
Wed Jun 30 13:19:54 -  6120 - ReadConfig: WARNING: line 14: Ignoring line: 'ProxyPass'    

Any suggestions?

I'll answer my own question. Turns out we were running a very old version of IIRF. I updated to the latest version, and ProxyPass works now.