I am trying to create a managed package. When I go into 'Package Manager', it says: "Your organization is configured to create unmanaged packages only. Unmanaged packages are not upgradeable. To create a managed package, you must be using Developer Edition. Sign up for Developer Edition" 

I did sign up for the Developer Edition, but still I cannot see the 'Packages' option in my setup menu. Any help would be appreciated. Thanks!

I am trying to create a managed package. When I go into 'Package Manager', it says: "Your organization is configured to create unmanaged packages only. Unmanaged packages are not upgradeable. To create a managed package, you must be using Developer Edition. Sign up for Developer Edition" 

I did sign up for the Developer Edition, but still I cannot see the 'Packages' option in my setup menu. Any help would be appreciated. Thanks!