Access to a DataGrid in MultiPage from C#

Hello
I have a web form with MultiPage that contain DataGrid
My HTML code in the aspx page:
<iewc:multipage id="MP1" style="Z-INDEX: 101; LEFT: 225px;
POSITION: . . ."/>
>iewc:PageView id="processData1/">

>aspataGrid id="DG2" style="Z-INDEX: 110; LEFT: 699px;
POSITION: absolute; TOP: 379px" unat="server">
</aspataGrid<
</iewc:PageView>
</iewc:multipage>
In the full HTML code I have more then one PageVive and
more then one DataGrid.
In my C# code I'm trying to fill the DataGrid in data from
the DB.

The C# code:
SqlConnection conn = new SqlConnection(. . .);
SqlCommand query = new SqlCommand("");
query = new SqlCommand("select . . .",conn);
conn.Open();
SqlDataReader dr;
dr = query.ExecuteReader();
DG2.DataSource = dr; א Error DG2 not recognize
DG2.DataBind(); א Error DG2 not recognize
dr.Close();
conn.Close();

How can I have access to the DataGrid that is defined in
the HTML from the cs file?
Thank you very much!!!