Dropdown list help please

I am attempting to fill in a datagrid based on a dropdown list
selection on a webform. If item one is chosen, a specific
dataadapter is loaded. I assumed I need to use the SelectedIndex
property of the dropdown list to make a comparison, but I can't get
it to work.

Here's an example of what I got so far. Can anyone tell me where
I've gone astray...

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim x As Integer = ddlMgrs.SelectedIndex()
If x = 0 And IsPostBack Then
dgManagers.DataSource = DsSGT1
dgManagers.DataMember = "State Guidelines Table"
dgManagers.Visible = True
daSGT.Fill(DsSGT1)
End If
DataBind()
End Sub

Help please...

Thanks...Troy