Could not find control 'ControlID' in ControlParameter 'ParamName' - html

Question

Ok guys, I know this question has been asked a million times. I've searched for days and none of the online solutions found actually work for me. Here's my code:
<asp:SqlDataSource
ID="SqlDataSource2"
runat="server"
ConnectionString="<%$ ConnectionStrings:ConnectionString %>"
ProviderName="<%$ ConnectionStrings:ConnectionString.ProviderName %>"
SelectCommand="SELECT VTPNAME, NETWORKKEY, FKVTPDOMAIN, VLANNUMBER, NETDESCRIPTION, BEGINNINGIP,
HOSTS, DEFAULTGATEWAY FROM NETWORK.NETWORK, NETWORK.VTPDOMAIN WHERE
NETWORK.FKVTPDOMAIN = VTPDOMAIN.VTPDOMAINKEY"
DeleteCommand="DELETE FROM NETWORK.NETWORK WHERE NETWORKKEY =: NETWORKKEY"
UpdateCommand="UPDATE NETWORK.NETWORK SET FKVTPDOMAIN =:updateFKVTP, VLANNUMBER = :VLANNUMBER,
NETDESCRIPTION = :NETDESCRIPTION,BEGINNINGIP = :BEGINNINGIP,
HOSTS = :HOSTS,DEFAULTGATEWAY = :DEFAULTGATEWAY WHERE NETWORKKEY = :NETWORKKEY"
InsertCommand="INSERT INTO NETWORK.NETWORK (VLANNUMBER,NETDESCRIPTION,BEGINNINGIP,HOSTS,DEFAULTGATEWAY,FKVTPDOMAIN) VALUES (:vlanNet,:descNet,:begIpNet,:hostNet,:defNet,:vtpdomainkey)">
<InsertParameters>
<asp:ControlParameter Name="vlanNet" ControlID="vlanTextbox" />
<asp:ControlParameter Name="descNet" ControlID="descTextbox" />
<asp:ControlParameter Name="begIpNet" ControlID="beginIPTextbox" />
<asp:ControlParameter Name="hostNet" ControlID="hostsTextbox" />
<asp:ControlParameter Name="defNet" ControlID="defaultGatTextBox" />
<asp:ControlParameter Name="vtpdomainkey" ControlID="vtpDomainFKDropDown" />
</InsertParameters>
<UpdateParameters>
<asp:ControlParameter Name="updateFKVTP" ControlID="vtpNameDropDownUpdate" />
</UpdateParameters>
</asp:SqlDataSource>
<asp:GridView
ID="GridView2"
runat="server"
AutoGenerateColumns="False"
DataSourceID="SqlDataSource2"
AllowPaging="True"
AllowSorting="True"
DataKeyNames="NETWORKKEY"
Width="650px"
OnRowUpdating="GridView2_RowUpdating">
<Columns>
<asp:CommandField HeaderText="Options" ShowDeleteButton="True" ShowEditButton="True" />
<asp:TemplateField HeaderText="VTP Domain" SortExpression="VTPNAME">
<EditItemTemplate>
<asp:DropDownList ID="vtpNameDropDownUpdate" runat="server" DataSourceID="SqlDataSource6" DataTextField="VTPNAME" DataValueField="VTPDOMAINKEY">
</asp:DropDownList>
</EditItemTemplate>
<ItemTemplate>
<asp:Label ID="Label2" runat="server" Text='<%# Bind("VTPNAME") %>'></asp:Label>
</ItemTemplate>
</asp:TemplateField>
Here's the actual error given:
Could not find control 'vtpNameDropDownUpdate' in ControlParameter 'updateFKVTP'.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.InvalidOperationException: Could not find control 'vtpNameDropDownUpdate' in ControlParameter 'updateFKVTP'.
Everything works as is supposed to, except the dropDownList. It will NOT find it, I have tried dollar signs, colons,underscore, you name it, to tell it where the control is and no result. They are in the same and they both lay one under the other, just as I posted it here. I got the first row to actually update because I tried the method where you right click on the dropdownlist while running and you "inspect the element" and copy and paste the whole ControlID string into the ControlParameter ControlID. The problem is, there are several rows, so it will only work for the one element I inspected and not all the other ones. Any help would be appreciated and thank you in advance for your time!
-Fernando

Answer 1

The DropDownList is inside The Template Control, so you should find the template control first.In this example template control is in 7th column of Gridview. after find template inside that you can find DropDownList :
protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)
{
var index = e.RowIndex;
var dropDownctr= GridView1.Rows[index].Controls[6].FindControl("vtpNameDropDownUpdate")
}