before you can add the populate list from array behavior, you need to first add the Create dynamic Array server behavior.
the work flow is:
-create the parent select list
-create the child select list
-create a recordset to return the categories
-create a recordset to return subcatagories
-Add parent list, populate it using categories recordset
-Add the Create Dynamic Array, this will use the subcategories recordset. Bind the pasrent ID, child ID and Child text values to the corresponding columns of the subcategories recordset
-add the Populate List from array behavior to the onchange event of the parent select list.
