"Auto Fit All Columns" in the Context menu hides my checkbox field in ListGrid

we are using Version v9.0p_2013-08-05 smart client

I have a ListGrid which has many columns and one of the column has only check box in order to select and do delete action.

After clicking Auto Fit All Columns in the context menu, the check box column hides totally.

We have done following setings on checkbox Field for our Application requirements

checkboxField.showDefaultContextMenu = false;
checkboxField.showTitle = false;
checkboxField.canGroupBy = false;
checkboxField.canDragResize = false;
checkboxField.canReorder = false;
checkboxField.canHide = false;
_dsObject.getField(checkboxField.name).canHilite = false;
_gridObject.setAutoFitWidth(checkboxField.name, false);

Pls explain, how to make it visible after doing Auto Fit All Columns.

Hope you would understand our support contract by seeing the user id.