Trouble validating with /check/referer

When I try to use the link I put on my .htpasswd protected page with the link http://jigsaw.w3.org/css-validator/check/referer, I get the error:

I/O Error: Basic realm="Ecert Development Area"

I am able to check the very same page by filling in the form at:
http://jigsaw.w3.org/css-validator/validator-uri.html

where it simply asks me for the username and password necessary to access the .htpasswd protected page.

Thanks for your attention!

Jim Ramsay