Not Allowed To Access Settings

We have the Redirection plug-in installed and it seems to be working since some URLs are still being redirected. But when I try to change some of the settings for the plug-in, I get this error:

“Sorry, you are not allowed to access this page.”

The URL I’m trying to reach is:

http://[sitename]/wp-admin/tools.php?page=redirection.php&sub=options

Any ideas what may have happened here or how I fix it? Thanks a bunch!