What am I doing wrong here? Declare war isn't an option in my drop down menu.

No ab, no missle, co fun.

GDI functions differently on solo servers. It does not limit your NW attack range. Instead, GDI prevents all special attacks unless you attack some country more than once over the whole reset. That country (and only that country you broke GDI on) would be able to use special attacks on you.

Declare War thus doesn't work on solo servers and have been disabled.

I attacked a country a month ago. He retals and sends an annoying message. I want to declare war for the late retal. How do I do that? He's in GDI.

You can't. You can attack him again though, as many time as you want, and if he does anything about it, then you can war him.

Note that if you attack him a second time, you open up to any/all special attacks from him on you. Until he does so (attacks you a second time), you cannot use special attacks on him.

So we just keep trading PS's? I did a SS and a PS back to back and the declare war option came up on the attack drop down menu but when I clicked it and hit "send attack" I got an error message.

Has he hit you twice? If so, then you can go to war with him. You don't need to declare. If he hasn't hit you twice, chances are you are about to get it where the sun don't shine.

It's like what I said in my post. If he does anything else to you, then you can make any attacks you want. And now that you did more hits, he can do anything he wants to you. It's only the first hit that's free.

So you've given him the option to FS you. You can keep PS ing him to goat him into it, but cannot special attack until he's hit you at least twice.