In markup set AutogenerateColumns="true" :
<asp:GridView ID="g1" AutoGenerateColumns= "true" runat="server"></asp:GridView>
Here's how I have tested your code:
In my markup I have the gridview.
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:GridView ID="g1" AutoGenerateColumns= "true" runat="server"></asp:GridView>
<br />
<asp:Label ID="lblErrorActivityGrid" runat="server" Text="Error Activity Grid"></asp:Label>
<br />
<asp:Label ID="lblActivityGridCount" runat="server" Text="Activity Grid Count"></asp:Label>
</div>
</form>
</body>
</html>
In my code, in page load I am adding a DataTable to a DataSet and calling bindGridView method:
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
DataSet ds = new DataSet();
DataTable dt = new DataTable();
dt.Columns.Add("Column1", typeof(string));
dt.Columns.Add("Column2", typeof(string));
ds.Tables.Add(dt);
for (int i=0; i<5; i++)
{
DataRow nw = ds.Tables[0].NewRow();
nw[0] = (i + 1).ToString();
nw["Column1"] = (i + 1).ToString();
nw["Column2"] = String.Format("Item {0}", i);
ds.Tables[0].Rows.Add(nw);
}
bindGridView(ds.Tables[0], g1, lblErrorActivityGrid, lblActivityGridCount);
}
}
private void bindGridView(DataTable dt, GridView grd, Label lblError, Label GrdRowCount)
{
grd.DataSource = dt;
grd.DataBind();
}
And here's the grid shows in my browser:
