Membership Plugin Upgrading Subscription redirects me to Membership Home Page

I am having problems upgrading from one subscription to another, if I disable the maintenance mode plugin I still get the same result. When I try to upgrade a subscription I am simply redirected to the Member's Home page instead of a payment gateway. I have been through all the setup tutorials and my configurations but have had no luck on getting this resolved. I believe it may be in my setup or configuration of the Subscriptions.

I am currently setup with Basic, Bronze, Silver and Gold Subscriptions and Levels.

Basic Subscription is free and has access to limited parts of the site as determined by Basic Level setup.

Setup: Serial / 1 year period / Price $0 / Basic Level - No subsequent Membership levels setup

If a Basic Member wishes they may "upgrade" to Bronze, Silver or Gold Membership at any time during their membership.

Bronze Subscription is $19.95 and has access to limited parts of the site as determined by Bronze Level setup and has access to Basic level Functions as well.

Setup: Serial / 1 year period / Price $19.95 / Bronze Level - No subsequent Membership levels setup

If a Bronze Member wishes they may "upgrade" to Silver or Gold Membership at any time during their membership.

Silver Subscription is $97.00 and has access to limited parts of the site as determined by Silver Level setup and has access to Bronze level Functions as well.

Setup: Serial / 1 year period / Price $97.00 / Silver Level - No subsequent Membership levels setup

If a Silver Member wishes they may "upgrade" to Gold Membership at any time during their membership.

Gold Subscription is $197.00 and has access to limited parts of the site as determined by Gold Level setup and has access to Silver level Functions as well.

Setup: Serial / 1 year period / Price $197.00 / Gold Level - No subsequent Membership levels setup

Basically each successive level has more rights than the one previous to it. But I desire that the Member may "upgrade" to a higher level at any time during their membership. They might even choose to skip a level and go from say Basic directly to Gold. Or they could simply cancel their subscription in which case it remains active for one year and then expires.

Any help would be appreciated.

Greg