ช่วยดู Code ให้ด้วยคะ dropdownlist ไม่แสดง จะทำให้เลือกตำแหน่งงานแล้วค่อยโชว์แผนกคะ

                <asp:DropDownList ID="ddPosition" runat="server" AutoPostBack="True" DataTextField="position"
                  DataValueField="position"  OnSelectedIndexChanged="ddPosition_SelectedIndexChanged"> 
                  <asp:ListItem Value="0" Text="เลือกตำแหน่งงาน"> </asp:ListItem> 
                </asp:DropDownList> 

                <asp:DropDownList ID="ddlDepartment" runat="server" DataTextField="DeptName" DataValueField="DeptName"> 
                </asp:DropDownList> 

    Public Sub PositionBind()
        Dim sqlQuery = "SELECT * FROM WorkPosition WHERE position = '" & ddPosition.SelectedValue & "'"
        Dim da As New SqlDataAdapter(sqlQuery, condb)
        da.Fill(ds, "select")
        dt = ds.Tables("select").Rows(0)

        ddPosition.SelectedValue = dt("position")

    End Sub
    Public Sub DepartmentBind()
        Dim sqlQuery = "SELECT * FROM tbDepartment WHERE DeptName = '" & ddlDepartment.SelectedValue & "'"
        Dim da As New SqlDataAdapter(sqlQuery, condb)
        da.Fill(ds, "select")

        dt = ds.Tables("select").Rows(0)

        ddlDepartment.SelectedValue = dt("DeptName")

    End Sub
    Protected Sub ddPosition_SelectedIndexChanged(sender As Object, e As System.EventArgs) Handles ddPosition.SelectedIndexChanged
        DepartmentBind()
    End Sub