Thanks for your kind reply on this matter.

Actually, i'd already taken care of the 2 points you mentioned. It really returns True for the TableUpdate() call, and the
CursorSetProp() is placed in Form.Load() method once and only once and the form is set to private data session.

Everything's normal until some day it just explode.

I tested the table using the 5-line code in my message, excuted in the command prompt, because i want to skip all
possible influence of the input form.

Any idea?