>My app uses a checkbox to manage mousemove services. My convention is to use 0 for off and 1 for on.
>
>Somtimes, CheckBox forgets its a number, and VFP messages Operand/Data Type error. And sure enoug, when I look at the state recorded at last "bomb", the checkbox type has changed from numberical to logical.
>
>Maybe I should swith to a true/false application of check box?
>
>Oh yeah, it's VFP-8 and the crash happens inside a treeview mouse move when the question is asked:
>

if MyCheckBox.Value=0
>   ....
>endif

>
>Thanks

I had the problem the other way around (in VFP6): If I didn't specify a value, it was sure to be numeric, where I expected it to be logical (logical is more "logical" for T/F questions, isn't it?)

Make sure you assign the correct value in the property sheet, Init() method, etc.

Another option is to change the code in your example as follows:

if empty(MyCheckBox.Value) && works both for 0 and .F.
   ....
endif

HTH,

Hilmar.