Cups Web Interface is Disabled

[Les Campbell]

When I attempt to load cups at http://local host631/admin the following 
message is displayed:

 Web Interface is Disabled

The web interface is currently disabled. Run "cupsctl WebInterface=yes" 
to enable it.

From the terminal I run "cupsctl WebInterface=yes" however I get 
"cupsctl: Internal Server Error".

How can I correct this problem and access the cups menu?

-Les-