by tahitiwahini on Thu Feb 15, 2007 8:03 pm
Two things can cause the "Illegal Fortification" message:
1) Even in unlimited fortification there must be a chain of countries you own leading from the source country to the destination country. Here the unlimited refers to the fact that you can make any number of fortifications, but all fortifications made must adhere to the chain requirement.
2) You may not fortify more armies than exist from your source country. For example, if you have 3 armies on Iceland, then you may fortify up to 2 armies from Iceland to any other country you own (as long as you can follow a chain of countries that you own to the destination country). You can't fortify 3 armies because that would leave a country without any army (that is, owned by nobody) which is not allowed.
I suspect you violated one of these rules. If not, you should submit a bug report in the Suggestions and Bug Report Forum.
Cheers,
Tahitiwahini