I am retreiving data from one page to another page on which i used to gridview to hold data using session

Now i am trying to delete row using deleting event

row is not getting deleted.

here is my c# code

protected void Page_Load(object sender, EventArgs e)
{
    DataTable dt;
    dt = (DataTable)Session["buyitems"];
    GridView1.DataSource = dt;
    GridView1.DataBind();
}

Row delete event

protected void GridView1_RowDeleting(object sender, GridViewDeleteEventArgs e)
{
    int index = Convert.ToInt32(e.RowIndex);
    DataTable dt = (DataTable)ViewState["buyitems"];
    dt.Rows[index].Delete();
    ViewState["buyitems"] = dt;
    GridView1.DataSource = dt;
    GridView1.DataBind();
}

please guide