Try to trim trailing spaces.

lcsource = 'ARCHIVE.' + ALLTRIM(udarc.field_name)
.controlsource = lcsource 
* or
.controlsource = 'ARCHIVE.' + ALLTRIM(udarc.field_name)

>Hi,
>
>I have a user defined screen in which I want to assign the controsource of a textbox to a value stored in a variable.
>
>This works fine:
>.controlsource='ARCHIVE.FAX'
>
>I have a table called udarc which holds the field_name I want to assign as the control source
>unfortunately when I do:
>
>lcsource='ARCHIVE.'+udarc.field_name
>.controlsource=lcsource
>
>I get:
>
>the data source for this object must be a variable reference.
>
>In this case of course the value in udarc.field_name is 'FAX'
>
>How do I get this to work?
>
>Thanks in advance,
>
>Brian