I have a list box that is bound to an object data source. I added a column, 
say ColumnC, to my typed data set (using the designer) and for the expression 
property  I entered

ColumnA + ': ' + ColumnB

When I preview the data in the designer I get exactly what I want.

Now I go over to the object data source on my web page, refresh it and 
refresh the schema. I can now see ColumnC as an option for the list box's 
data text field. However, when I run the page nothing shows up in the list 
box. However, when I view the page source, I see that the data value field 
did render.

Next I put in a value (instead of the default DBNull) for the DefaultValue 
property.  After going through the whole exercise of refreshing and such 
again, I run the page and the default value I put in is returned in the list 
box.

Does anyone know what I missed? It must be something stupid.

Thanks ...