Dropdownlist does not update after adding update panel

I have multiple dropdownlist box all querying the same column, same table and from the same database. For example under memberID column i have the following IDs.
1. 12345 2. 23456 3. 34567
And i have 3 different dropdownlist box as shown below
<asp:DropDownList ID="memberID3" runat="server" Visible="false" OnSelectedIndexChanged="ddlpid3_SelectedIndexChanged" > </asp:DropDownList> <asp:DropDownList ID="memberID1" runat="server" Visible="false" OnSelectedIndexChanged="ddlpid1_SelectedIndexChanged"> </asp:DropDownList> <asp:DropDownList ID="memberID2" runat="server" Visible="false" OnSelectedIndexChanged="ddlpid2_SelectedIndexChanged"> </asp:DropDownList>


I added update panel between the dropdownlist so as to allow my dropdownlist to refre ...