Step 1. Make sure you have /oper'ed (/whois YOURNICK and check for "is an IRC operator" or similar)
Step 2. Make sure you are identified to a nick that appears in /os staff as Root (NOT Admin or Oper) To check to see if you are identified use /ns status YOURNICK if it returns anything OTHER then 3 you are NOT identified.
If you still get "Access Denied" then, well I dont know what else to suggest.