Data of textboxes and dropdownlist display in gri

<asp:Content ID="Content2" ContentPlaceHolderID="MainContent" Runat="Server">
    <asp:ToolkitScriptManager ID="ToolkitScriptManager1" runat="server">
    </asp:ToolkitScriptManager>
         <div class="ContentClass">
         <asp:TabContainer ID="AssetTransactionTab" runat="server" ActiveTabIndex="0" CssClass="Tab"   Width="794px" Height="290px">
         <asp:TabPanel ID="NewTransaction"  runat="server"  HeaderText="New Transaction" >
         <ContentTemplate>

<asp:UpdatePanel ID="DetailUpdatePanel"  runat="server">
             <ContentTemplate>
            <table align="center" style="width: 666px">
             <tr>
             <td class="lableColumn"><asp:Label ID="lblAssetID" runat="server" Text="Asset ID:"></asp:Label> </td>
             <td><asp:DropDownList ID="ddlAssetID" runat="server"
                     DataSourceID="ddlAssetIDSource" DataTextField="AssetDescription"
                     DataValueField="AssetID" CssClass="ddlstyle"></asp:DropDownList>
                 <asp:SqlDataSource ID="ddlAssetIDSource" runat="server"
                     ConnectionString="<%$ ConnectionStrings:DeemahAssetConnectionString %>"
                     SelectCommand="GetAssetDropDown" SelectCommandType="StoredProcedure">
                 </asp:SqlDataSource>
                 </td>
                   <td class="lableColumn"><asp:Label ID="lblEmployeeID" runat="server" Text="Employee ID:"></asp:Label> </td>
              <td><asp:DropDownList ID="ddlEmployeeID" runat="server"
                      DataSourceID="ddlEmployeeIDSource" DataTextField="EmployeeName"
                      DataValueField="EmployeeID" CssClass="ddlstyle" Width="200px"></asp:DropDownList>
                  <asp:SqlDataSource ID="ddlEmployeeIDSource" runat="server"
                      ConnectionString="<%$ ConnectionStrings:DeemahAssetConnectionString %>"
                      SelectCommand="GetEmployeeDropDown" SelectCommandType="StoredProcedure">
                  </asp:SqlDataSource>
                 </td>
             </tr>
             <tr>
              <td class="lableColumn"><asp:Label ID="lblSupplierID" runat="server" Text="Supplier ID:"></asp:Label></td>
             <td><asp:DropDownList ID="ddlSupplierID" runat="server"
                     DataSourceID="ddlSupplierIDSource" DataTextField="VendorName"
                     DataValueField="VendorID" CssClass="ddlstyle"></asp:DropDownList>
                 <asp:SqlDataSource ID="ddlSupplierIDSource" runat="server"
                     ConnectionString="<%$ ConnectionStrings:DeemahAssetConnectionString %>"
                     SelectCommand="GetVendorDropDown" SelectCommandType="StoredProcedure">
                 </asp:SqlDataSource>
                 </td>
                 <td class="lableColumn"><asp:Label ID="lblIssuedReceivedDate" runat="server" Text="Issued/Received Date:"></asp:Label></td>
             <td><asp:TextBox ID="txtIssuedReceivedDate" runat="server" CssClass="txtstyle"></asp:TextBox>
              <asp:ImageButton ID="imgIssuedReceivedDate" runat="server" ImageUrl="~/Images/btn_calicon.gif" />
                 <asp:CalendarExtender ID="calIssuedReceivedDate" runat="server" TargetControlID="txtIssuedReceivedDate" PopupButtonID="imgIssuedReceivedDate">
                 </asp:CalendarExtender></td>
             </tr>
              <tr>
               <td class="lableColumn"><asp:Label ID="lblLocationID" runat="server" Text="Location ID:"></asp:Label></td>
             <td><asp:DropDownList ID="ddlLocationID" runat="server"
                     DataSourceID="ddlLocationSource" DataTextField="LocationName"
                     DataValueField="LocationID" CssClass="ddlstyle"></asp:DropDownList>
                 <asp:SqlDataSource ID="ddlLocationSource" runat="server"
                     ConnectionString="<%$ ConnectionStrings:DeemahAssetConnectionString %>"
                     SelectCommand="GetLocationDropDown" SelectCommandType="StoredProcedure">
                 </asp:SqlDataSource>
                 </td>
                 <td><asp:Button ID="btnAdd" runat="server" Text="ADD" CssClass="Btn"
                         onclick="btnAdd_Click"></asp:Button></td>
                 </tr>
             </table>
            </ContentTemplate>
             </asp:UpdatePanel>
             <div>
             <asp:UpdatePanel ID="GridUpdatePanel" runat="server">
             <ContentTemplate>
             <asp:GridView ID="GriDisplay" runat="server" AutoGenerateColumns="False">
             <Columns>
             <asp:TemplateField  HeaderText="Asset">
             </asp:TemplateField>
             <asp:TemplateField  HeaderText="Location">
             </asp:TemplateField>
             </Columns>
             </asp:GridView>
             </ContentTemplate>
             </asp:UpdatePanel>
             </div>
         </div>
         </ContentTemplate>
         </asp:TabPanel>
         </asp:TabContainer>
         </div>
</asp:Content>

protected void btnAdd_Click(object sender, EventArgs e)
  {
      ArrayList arr = new ArrayList();
      arr.Add(int.Parse(ddlAssetID.SelectedValue).ToString());
      arr.Add(int.Parse(ddlEmployeeID.SelectedValue).ToString());
      GriDisplay.DataSource = arr;
      GriDisplay.DataBind();
  }