AJAX :: Only One Of 2 Ddl's Causes Page Refresh Within Updatepanel In Detailsview?

I have 2 ddls (cascading that does not use the AJAX cascading ddl) within an updatepanel within an EditTemplate field in a DetailsView. Changing the first ddl causes a full page refresh (this is the problem I am trying to overcome), but changing the second ddl does not. The second ddl is set to autopostback as well because of other logic (if user selects value "Add" a modal pops up to add a new option to the database).

Now the first, does a call out to a class to handle setting the list of values for the second...that is the only difference I can tell between the two, but I wouldn't think that would cause the issue because it is within an updatepanel.

Here's the code:

[Code]....

On Selected Index Change code for each

For the First:

[Code]....

For the Second:

Protected Sub ddlModel_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs)
Dim ddlModel As DropDownList = dtlBikes.FindControl("ddlModel")
Dim ddlMfg As DropDownList = dtlBikes.FindControl("ddlMfg")
If ddlModel.SelectedValue = "Add" Then 'Add New Record
txtDDLName.Value = "ddlModel"
txtDtlsViewName.Value = "dtlBikes"
txtItemType.Value = "BikeModel"
txtParentID.Value = ddlMfg.SelectedValue
txtNewItem.Text = ""
txtNewItem.Focus()
lblNewItem.Text = "Enter New Model:"
modInsertItem.Show()
End If
End Sub