Need help in Grid object

[startup]

i need a working example to deselect cell in Grid object

from the free manual i try

TotalColumn = Grid.GetColumnCount("Grid1");
TotalRow = Grid.GetRowCount("Grid1");
-- Set the selected cells
Grid.SetSelectedRange("Grid1", 0, 0, TotalColumn / 2, TotalRow / 2, true, true);

that
Select half of the cells in the object "Grid1"

but when i try the following cod in another button

TotalColumn = Grid.GetColumnCount("Grid1");
TotalRow = Grid.GetRowCount("Grid1");
-- Set the selected cells
Grid.SetSelectedRange("Grid1", 0, 0, TotalColumn / 2, TotalRow / 2, false , true);

that dos not deSelect the cells in the object "Grid1"
why ?
and how can i deselect a cell ??

plz i need a working example

[startup]

ok
if the cell in row1 col1 is selected
i need just a working code to deselect that cell