Htaccess not picking up bogus URLs

Google webmaster tools problem

[Lorel]

I have the following in my htaccess file for a custom 404 page and it works when I type in a bogus URL.

ErrorDocument 404 /missing.html

However, Google's Webmaster tools keeps recording bogus URLS. I've also noticed that my traffic starts dropping after a few weeks unless I keep removing those error notices.

Is there something else I can do to prevent these error notices?

[g1smd]

What status code is shown in WMT?

If it is 404 and you don't have that URL in any links within your site, then there's nothing more to do.

Google is letting you know that they found URLs that return 404. If that's what those URLs are supposed to do, then there's nothing to fix.