How to get nested gridview row count

Hello i have these tow grids paretnt grid view is gvAgreement and child grid is gvProducts.
I am trying to get gvProducts row count .
so i used this blow code
  protected void OnRowDataBound(object sender, GridViewRowEventArgs e)        {if (e.Row.RowType == DataControlRowType.DataRow)                {                    string AgreementId = gvAgreement.DataKeys[e.Row.RowIndex].Value.ToString();                    GridView gvProducts = e.Row.FindControl("gvProducts") as GridView;                    gvPro ...