Inline Editing Waterfall DropDownlist

Question

Hello All
I am new to inline editing.
I need to be able to create a row in which one ddl waterfalls off of another. 
I have the first ddl populated with its proper data.  How do I fire off the event for the first ddl to populate the vaules that pertain the items in the first dropdown list.
I tried the following but got a Requires withEvents  variable:
Protected Sub ddlDiskArrayMake_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles ddlDiskArrayMake.SelectedIndexChanged
Dim ta As New dalDataCenter_DefsTableAdapters.spGetDiskArrayModelByMakeTableAdapter
With ddlDiskArrayModel
.DataSource = ta.Get_DAModelsByMake(ddlDiskArrayMake.SelectedValue)
.DataTextField = "Disk_Array_Model"
.DataValueField = "Disk_Array_Model"
.DataBind()
.Items.Insert(0, New ListItem("-Select-", "-Select-"))
End With
End Sub
 
 
 
Much appreciated
Pat