At least the first few times that I have tried it. Any reasonable explanations and/or help?
It’s disabled on this board. If you want something edited, drop a line to one of the mods who is in charge of the board and they’ll take care of it.
Yep. andygirl’s right. If you look at the bottom of each thread and at the top of each reply page, in the Forum Rules list, you’ll see: “Changes: Messages CANNOT be edited by their author. Messages CANNOT be deleted by their author.”
It would cut down on the number of posts where I end up writing a second one, just to clarify the first.
Oh wait, that would drive my post count down.
Never mind. 
I like it a lot at sites that have it.
Since sites like that have a lot of people editing, nobody is upset or confused. It’s just normal.
Soupy:
The sad thing is, trolls have abused the function to the point where it’s untenable. They would post something obscene and then once a number of replies had been gotten, they would edit their post and make it innocuous, then flame us for making thing up and unfairly attacking him. It got to be a hassle.
Keep track of old versions of a post for a set period of time (small click here to view changes link).
To avoid overwhelming the db, have them expire after a while.
The board is getting closer to overload with every day and every member that goes by.
We need less functions or yet another ( expensive ) server to keep up.