I don't think I am using table buffering properly. Can someone help me?

I turn on table buffering in the Init of my Form. Then, later on I do the command =TABLEUPDATE(.T.) and get the error message "Function requires row or table buffering mode." The weird thing is that I pressed the Save button (containing the TABLEUPDATE function) a few times in a row before I got the error message, but pressed the Edit button in between. So it is apparently working sometimes.

I do the command =TABLEREVERT(.T.) for my Cancel button and it works fine. I don't get any error messages. And it reverts my changes.

What causes table buffering to turn off on its own? Am I correct in setting up table buffering in the Init of the Form? And using the TABLEUPDATE function in the Save button and the TABLEREVERT functino in the Cancel button?

Thanks for the answers. I don't get it. It seems fairly straightforward.