getting redirect loop

Disclaimer: I'm new to all this...

When trying to use a Vanity irule I get a redirect loop in Google or site can not be found in IE. When doing a curl the results are positive. Any suggestions for troubleshooting?

when HTTP_REQUEST { if { ([HTTP::host] equals "hostqalb.ad.domain.com") } { HTTP::redirect "http://hostqalb.ad.domain.com/hostportal" } }