I don't think anyone can help if you don't say what scenario you're trying to play!
You might be better off asking in the scenario's own thread. Don't forget to specify what version of Civ III you have (Play the World, Conquests, etc) and precisely where you installed the scenario.
Or if this is a scenario you're making yourself, what exactly have you done?
And did you include files for those units? rename the folder and ini to the name you chose?
That shouldn't make a difference. Did you edit the PediaIcons file correctly?