My crew has been having gobs of issues with this lately, so you're not alone. They're always sending me messages for their cowriters in other stories.
Merz is right. If the name isn't from a name in a story you're looking at, you won't be able to reply to them unless you go out to the main Storycrafter page and go to your messages from there.
And even then, you have to doublecheck both the name of the person you're replying to, and the name it brings up for you. It's liable to pick whatever name of yours it wants unless you change it A problem if you don't want the person to know your alter egos.
