>Alan,
>
>A checkbox can be either numeric or logical depending on its controlsource. You would be much better off refering to the controlsource instead of the checkbox.value for your code. For example, if the field name is ThisIsChecked then your code would refer to Alias.ThisIsChecked and not Grid.Column.CheckBox.Value

Thanks everyone for your help - I got the thing to work correctly by referring to the controlsource instead of the value of the checkbox.