I believe there was an update released for Colonization which fixed a few things.
edit - having checked my copy (not the original disks, but the copy of what was on my A1200's HDD when I backed it up), I can't see any obvious evidence that I ever updated it. However, it is v1.11 which is apparently the latest version.
Which version are you running? It shows on the very first menu screen.
edit2 You might find this worthwhile reading:
http://www.colonizationfans.com/game-topics.html(sadly there are no patches there for the Amiga version, and only a vague mention of there even being an Amiga version)
