I have a chat box that refresh every 7 seconds by a timer the problem is that the div is scrolling top each time the timer I have tried to add the following

Page.ClientScript.RegisterClientScriptBlock(this.GetType(), "focus", "document.getElementById('divMessages').scrollTop = document.getElementById('divMessages').style.height;", true);

to the timer tick but it doesn't work ticks here is my code

            <table border="0" cellpadding="0" cellspacing="0">
                <tr>
                    <td style="width: 500px;">
                        <div id="divMessages" style="background-color: White; border-color:Black;border-width:1px;border-style:solid;height:300px;width:592px;overflow-y:scroll; font-size: 11px; padding: 4px 4px 4px 4px;" onload="SetScrollPosition();" onresize="SetScrollPosition()">
                            <asp:Literal Id="litMessages" runat="server" />
                        </div>
                    </td>
                    <td>&nbsp;</td>
                    <td>
                        <div id="divUsers" style="background-color: White; border-color:Black;border-width:1px;border-style:solid;height:300px;width:150px;overflow-y:scroll; font-size: 11px;  padding: 4px 4px 4px 4px;">
                           <asp:Literal Id="litUsers" runat="server" />
                        </div>
                    </td>
                </tr>
                <tr>
                    <td colspan="3">
                        <asp:TextBox Id="txtMessage" onkeyup="ReplaceChars()" onfocus="SetToEnd(this)" runat="server" MaxLength="100" Width="500px" />
                        <asp:Button Id="btnSend" runat="server" Text="Send" OnClientClick="SetScrollPosition()" OnClick="BtnSend_Click" />
                        &nbsp;
                        <b>Color:</b> <asp:DropDownList Id="ddlColor" runat="server">
                            <asp:ListItem Value="Black" Selected="true">Black</asp:ListItem>
                            <asp:ListItem Value="Blue">Blue</asp:ListItem>
                            <asp:ListItem Value="Navy">Navy</asp:ListItem>
                            <asp:ListItem Value="Red">Red</asp:ListItem>
                            <asp:ListItem Value="Orange">Orange</asp:ListItem>
                            <asp:ListItem Value="#666666">Gray</asp:ListItem>
                            <asp:ListItem Value="Green">Green</asp:ListItem>
                            <asp:ListItem Value="#FF00FF">Pink</asp:ListItem>
                        </asp:DropDownList>
                        &nbsp;
                        <asp:Button Id="btnLogOut" Text="Log Out" runat="server" OnClick="BtnLogOut_Click" />
                    </td>
                </tr>
            </table>  
            <script type="text/javascript">
                var div = document.getElementById('divMessages');
                div.scrollTop = div.style.height;

                </script>              
        </ContentTemplate>
    </asp:UpdatePanel>