I cannot seem to push upgrades to my subscribers.

The version;
- Is a managed release (not beta)
- Has passed security review
- Is up on the Appexchange

The application;
- Is Apex Certified
- Has the Aloha Status

The development org;
- Has push upgrades enabled
- Has pushed upgrades in the past
- Can push upgrades up to version 2.2.2
- The latest version is 2.2.7

Can anyone else see anything that I may have missed out here? These push upgrades are a pain!!!