DataTable.Compute works in one DataTable but not in other DataTable

Hi my code is this:
protected DataTable FillDatosgv1(int ini, int fin) { SqlConnection cnx = Conexion.Conectar(); SqlCommand cmd_deg = new SqlCommand("SELECT moneda_id, moneda, anio, total FROM v_ServDeu_x_Año_x_Moneda_Totales_Simu", cnx);//deg SqlDataAdapter adp_deg = new SqlDataAdapter(cmd_deg); DataTable dt_todo = new DataTable(); DataSet dataSet_todo = new DataSet(); adp_deg.Fill(dt_todo); int cant_filas = dt_todo.Rows.Count; int[] aniosArray = new int[cant_filas]; decimal[] totalesArray = new decimal[cant_filas]; int[] aniosArray_2 = new int[cant_filas]; decimal[] totalesArray_2 = new decimal[cant_filas]; DataTable dt = new DataTable(); DataSet dataSet = new DataSet(); dt.Columns.Add("anio"); dt.Columns.Add("total"); for (int x = 0; x < cant_filas; x&# ...