You have to explicitly hide the other column.. I'm guessing your data source only has two columns, therefore the webcombo is showing two columns.. If it had 3, 6.. it'd show all of those, so what you have to do is to set the hidden property to true for all those columns you don't want to be displayed and leave false the one column you're using as datatextfield.
"Programming is an art form that fights back" _ Se habla español.