TDataSetTableProducer - 'Class not registered'?

After adding the DataSetTableProducer to my Web application and setting
the properties, when I click on the ellipse in the 'Columns' property to
edit the table, I get the 'Class not registered' error message. Do I
have a defective version of Delphi 5 (I thought all the icon selections
would have been registered during installation) or am I missing
something before I try to edit the DataSetTableProducer table?