I don't understand why the following strange thing happened in my form:
In a form's INIT, it has

set order to inv_no && inv_no is the index of a table
append blank
thisform.grid1.setfocus()

OK, fine, the user can add new data in the grid for the first row.
At the last column of the grid, I have the following in the Keypress event:

append blank
thisform.grid1.refresh()

OK, it is still fine, the user can add data in the 2nd row. But then
when he pressed the enter at the end of 2nd row, it supposted will move to the 3rd row to allow enter new data but the fact is that the cursor moved to the first column of row 2.
If I cancel the 'set order ot inv_no' in the form's INIT, this problem disappears, why? But I need the 'set order' to find the biggest inv_no, I cannot cancel it.