I am having problems upgrading ships. I either missed something or it is a bug. Most likely I missed it for I am new to this game. Whenever a new ship upgrade comes available, I don't seem to be able to upgrade that class of ship. I see the upgrade screen with the items that can be upgraded but the cost to upgrade is shown as zero. What is the sequence to upgrade? Do I have to manually upgrade that class of ship first, save it as the same name and then request that all ships of that class be upgraded? How can you upgrade stock ships if you cannot save them with the same name?