Changing Unit Upgrade in Civ 4 Warlords

[cml_nine]

Has anyone tried to make the Explorer unit upgradable in the later stages of the game. eg. to a Marine for example. It seems relatively straightforward to change the upgrade path for other units but when you add the XML to upgrade an Explorer, it causes an error. Is this because the upgrade has to be enabled elsewhere outside UnitInfos? Any thoughts?

 

[Yakk]

Try typing in what you are actually doing, in [ code ] tags.