Redirect not kicking in

Hi,

I'm trying to redirect certain browsers but somehow it doesn't work for me.  Testing on a blank IIS, using default site, redirecting IE6:

<rule name="unsupported browsers" enabled="true" stopProcessing="true"><match url=".*" /><action type="Redirect" url="switch.htm" /><conditions><add input="{HTTP_USER_AGENT}" pattern="MSIE\+6\.0" /><add input="{URL}" pattern="switch.htm" negate="true" /></conditions></rule>

Pattern tests OK, however redirect doesn't happen.  I'm not sure Failed Req Trace will work here?

Please help me figure it out.

Thanks.