>Hi!
>
>I am having trouble creating a Calulated ControlSource for a TextBox on a Form.
>
>When I specify an expression as the ControlSource of the TextBox I get an error "The data source for this object must be a variable reference"
>
>e.g. ThisForm.TxtFileName.ControlSource = "juststem(filename) + '.'+ justext(filename)" where filename is a memo field.
>
>I have tried a few different ways but none of them seem to work.

VFP seems to choke if expressions for ControlSource gets too complex. Just how complex is too complex, I've never figured out.

One way to get around it is to use a UDF:

ThisForm.TxtFileName.ControlSource = "MyUDF(filename)"

FUNCTION MyUDF
LPARAMETERS tcFileName

RETURN juststem(tcfilename) + '.'+ justext(tcfilename)