GridView Paging Problem

I am using paging in Grid view
<asp:GridView ID="gridviewOrganization" runat="server" AutoGenerateColumns="False"
                                onrowcommand="gridviewOrganization_RowCommand"
                                onpageindexchanging="gridviewOrganization_PageIndexChanging" PageSize="2" AllowPaging="true">

public void getExistOrganization()
    {
        string Error = "";
        ArrayList arrOrg = new ArrayList();
        User u = null;
        dr ...