spoof:// format error

well you didnt format the spoof url correctly

the format should be like
spoof://www.test.com;ref://www.spooftest.org


a place to test the referrer would be as spoof url:
spoof://refspoof.mozdev.org/referrer.php;ref://www.spooftest.org
or with more properties
spoof://l4x.org/i.php;ref://www.spooftest.org

for a litte fun this was the error catch prior to this page.
note that this is by itself a spoof url as they seem to also have protected from direct/deep linking by a ref test :)