UBB Classic is 6.7.3. I upgraded several months ago from whatever was available Dec. 2003. ~6.3

I can see memberlist.cgi inside the Members directory.

Tried the shorter entry Gizmo recommended, and got the same error message:
Checking... You entered the wrong path to the members directory

I also checked and made sure all directory and file permissions were the same as the old site. I had to set permissions higher on the new site, but that did not help -- tried both absolute and local paths.