Trying to use pessimistic table buffering to undo changes when desired.

CURSORSETPROP("Buffering", 4, 'Department') && form LOAD

..... change record

..... change another record (get error)

ThisForm.Release() && OK button

CURSORSETPROP("Buffering", 1, 'Department') && form UNLOAD

However above works OK if I change the one record only.
If I try to change more than one record I get error 2072
"Cursor cannot be modified because it contains an unsaved record."

Tried putting TableUpdate(1) but still same error.
The table is a free table and is USE AGAIN as Department
Any ideas?