Image disappears after click event

Question

Hi,

I am working on nested gridview concept...

Here is the html source and the javascript function ... The image in the gridview disappears after a user clicks on it.. Why is it happening so? Please correct me.

<script type="text/javascript">
  function expandcollapse(obj,row)
  {
  var div = document.getElementById(obj);
  var img = document.getElementById('img' + obj);
 
  if (div.style.display == "none")
  {
  div.style.display = "block";
  if (row == 'alt')
  {
  img.src = "minus.gif";
  }
  else
  {
  img.src = "minus.gif";
  }
  img.alt = "Close to view other item location";
  }
  else
  {
  div.style.display = "none";
  if (row == 'alt')
  {
  img.src = "plus.gif";
  }
  else
  {
  img.src = "plus.gif";
  }
  img.alt = "Expand to show item location";
  }
  }
  </script>
===========================================
 <asp:GridView ID="GridView1" AllowPaging="True"
  AutoGenerateColumns="false" DataSourceID="SqlDataSource1" DataKeyNames="ItemID"
  ShowFooter="true" Font-Size="8.25pt"
  Font-Names="Tahoma" runat="server"
  Width="800px" onrowdatabound="GridView1_RowDataBound"
  BorderColor="#666699" BorderStyle="Solid">
 
  <HeaderStyle BackColor="AliceBlue" ForeColor="#666699"/>
  <FooterStyle BackColor="White" />
  <Columns>
  <asp:TemplateField>
  <ItemTemplate>
  <a href="javascript:expandcollapse('div<%# Eval("ItemID") %>', 'one');">
  <img id="imgdiv<%# Eval("ItemID") %>" alt="Click to show/hide item location <%# Eval("ItemID") %>"  width="9px" style="border:0"  src="images/plus.gif"/>
  </a>
  </ItemTemplate>
  </asp:TemplateField>
 
  <asp:TemplateField HeaderText="Item ID">
  <ItemTemplate>
  <asp:Label ID="lblItemID" runat="server" Text='<%#Eval("ItemID") %>'></asp:Label>
  </ItemTemplate>
  <EditItemTemplate>
  <asp:Label ID="lblItemID" runat="server" Text=""></asp:Label>  </EditItemTemplate>
  <FooterTemplate>
  <asp:Label ID="lblItemID" runat="server" Text=""></asp:Label>
  </FooterTemplate>
  </asp:TemplateField>
 
  <asp:TemplateField HeaderText="Item Name">
  <ItemTemplate>
  <asp:Label ID="lblitemname" runat="server" Text='<%#Eval("ItemName") %>'></asp:Label>
  </ItemTemplate>
  <EditItemTemplate>
  <asp:TextBox ID="txtitemname" runat="server" Text='<%#Eval("ItemName") %>' Font-Names="Tahoma" Font-Size="8.25pt"></asp:TextBox>
  </EditItemTemplate>
  <FooterTemplate>
  <asp:TextBox ID="txtitemname" runat="server" Text="" Font-Names="Tahoma" Font-Size="8.25pt"></asp:TextBox>
  </FooterTemplate>
  </asp:TemplateField>
 
  <asp:TemplateField HeaderText="Item Code">
  <ItemTemplate>
  <asp:Label ID="lblitemcode" runat="server" Text='<%#Eval("ItemCode") %>'></asp:Label>
  </ItemTemplate>
  <EditItemTemplate>
  <asp:TextBox ID="txtitemcode" runat="server" Text='<%#Eval("ItemCode") %>' Font-Names="Tahoma" Font-Size="8.25pt"></asp:TextBox>
  </EditItemTemplate>
  <FooterTemplate>
  <asp:TextBox ID="txtitemcode" runat="server" Text="" Font-Names="Tahoma" Font-Size="8.25pt"></asp:TextBox>
  </FooterTemplate>
  </asp:TemplateField>
 
  <asp:TemplateField HeaderText="Group Name">
  <ItemTemplate>
  <asp:Label ID="lblGroupName" runat="server" Text='<%#Eval("GroupName") %>'></asp:Label>
  </ItemTemplate>
  <EditItemTemplate>
  <asp:TextBox ID="txtgroupname" runat="server" Text='<%#Eval("GroupName") %>' Font-Names="Tahoma" Font-Size="8.25pt"></asp:TextBox>
  </EditItemTemplate>
  <FooterTemplate>
  <asp:TextBox ID="txtgroupname" runat="server" Text="" Font-Names="Tahoma" Font-Size="8.25pt"></asp:TextBox>
  </FooterTemplate>
  </asp:TemplateField>
  <%-- <asp:BoundField DataField="ItemID" HeaderText="Item ID" />
  <asp:BoundField DataField="ItemName" HeaderText="Item Name" />
        <asp:BoundField DataField="ItemCode" HeaderText="Item Code" />
        <asp:BoundField DataField="GroupName" HeaderText="Group Name" />--%>
        <asp:CommandField HeaderText="Edit" ShowEditButton="True" />
        <asp:TemplateField HeaderText="Delete">
  <ItemTemplate>
  <asp:LinkButton ID="linkDeleteItem" CommandName="Delete" runat="server">Delete</asp:LinkButton>
  </ItemTemplate>
  <FooterTemplate>
  <asp:LinkButton ID="linkAddItem" CommandName="AddCustomer" runat="server">Add</asp:LinkButton>
  </FooterTemplate>
  </asp:TemplateField>
       
        <asp:TemplateField>
        <ItemTemplate>
        <tr>
  <td colspan="100%">
  <div id="div<%# Eval("ItemID") %>" style="display:none;position:relative;left:15px;OVERFLOW: auto;WIDTH:97%" >
  <asp:GridView ID="GridView2" AllowPaging="True" AllowSorting="true" BackColor="White" Width="100%" Font-Size="X-Small"
  AutoGenerateColumns="false" Font-Names="Verdana" runat="server" DataKeyNames="ItemID" ShowFooter="true"
 
 
  BorderStyle="Double" BorderColor="#0083C1">
  <RowStyle BackColor="Gainsboro" />
  <AlternatingRowStyle BackColor="White" />
  <HeaderStyle BackColor="AliceBlue" ForeColor="#666699"/>
  <FooterStyle BackColor="White" />
  <Columns>
  <asp:TemplateField>
  <ItemTemplate>
  <asp:Label ID="lblocid" Text='<%#Eval("Item_LocationID") %>' runat="server"></asp:Label>
  </ItemTemplate>
  <EditItemTemplate>
  <asp:Label ID="lblocid" Text='<%#Eval("Item_LocationID") %>' runat="server"></asp:Label>
  </EditItemTemplate>
  <FooterTemplate>
  <asp:Label ID="lblocid" Text="" runat="server"></asp:Label>
  </FooterTemplate>
  </asp:TemplateField>
 
  <asp:TemplateField>
  <ItemTemplate>
  <asp:Label ID="lblitemid" runat="server" Text='<%#Eval("ItemID") %>'></asp:Label>
  </ItemTemplate>
  <EditItemTemplate>
  <asp:Label ID="lblitemid" runat="server" Text='<%#Eval("ItemID") %>'></asp:Label>
  </EditItemTemplate>
  <FooterTemplate>
  <asp:Label ID="lblitemid" runat="server" Text=""></asp:Label>
  </FooterTemplate>
  </asp:TemplateField>
 
  <asp:TemplateField>
  <ItemTemplate>
  <asp:Label ID="lbllocname" runat="server" Text='<%#Eval("LocationName") %>'></asp:Label>
  </ItemTemplate>
  <EditItemTemplate>
  <asp:TextBox ID="txtlocname" Text='<%#Eval("LocationName") %>' runat="server" Font-Names="Tahoma" Font-Size="8.25pt"></asp:TextBox>
  </EditItemTemplate>
  <FooterTemplate>
  <asp:TextBox ID="txtlocname" Text="" runat="server" Font-Names="Tahoma" Font-Size="8.25pt"></asp:TextBox>
  </FooterTemplate>
  </asp:TemplateField>
 
  <asp:TemplateField>
  <ItemTemplate>
  <asp:Label ID="lblstore" Text='<%#Eval("StoreName") %>' runat="server"></asp:Label>
  </ItemTemplate>
  <EditItemTemplate>
  <asp:TextBox ID="txtstore" Text='<%#Eval("StoreName") %>' runat="server" Font-Names="Tahoma" Font-Size="8.25pt"></asp:TextBox>
  </EditItemTemplate>
  <FooterTemplate>
  <asp:TextBox ID="txtstore" Text="" runat="server" Font-Names="Tahoma" Font-Size="8.25pt"></asp:TextBox>
  </FooterTemplate>
  </asp:TemplateField>
 
  <%--<asp:BoundField DataField="Item_LocationID" HeaderText="Item Location ID" />
  <asp:BoundField DataField="ItemID" HeaderText="Item ID" />
  <asp:BoundField DataField="LocationName" HeaderText="Location" />
  <asp:BoundField DataField="StoreName" HeaderText="Store" />--%>
 
        <asp:CommandField HeaderText="Edit" ShowEditButton="True" />
        <asp:TemplateField HeaderText="Delete">
  <ItemTemplate>
  <asp:LinkButton ID="linkDeleteItemL" CommandName="Delete" runat="server">Delete</asp:LinkButton>
  </ItemTemplate>
  <FooterTemplate>
  <asp:LinkButton ID="linkAddItemL" CommandName="AddOrder" runat="server">Add</asp:LinkButton>
  </FooterTemplate>
  </asp:TemplateField>
  </Columns>
  </asp:GridView>
  </div>
  </td>
  </tr>
        </ItemTemplate>       
        </asp:TemplateField>       
      </Columns>
  </asp:GridView>