Maintenence Mode plugin won’t let me view my site

Hi,
I’m using the latest version of the Maintenence Mode plugin for one of my websites at the moment. It’s supposed to allow logged-in administrators to access the front-end site but it’s not letting me – whenever I try to view or preview pages I just get taken to the maintenence mode splash screen. Obviously it’s not much use to me if I can’t see the site while I’m maintaining it! I actually saw it recommended as a better alternative to a plugin where someone was having the same problem, so I’m not sure what could be wrong. Can anybody help? Is this a user permissions error? My site doesn’t have any registered users other than myself, and as far as I can see, I have administrator privileges.