保存键大于10的数组时发生未定义的偏移量错误

Question

我有以下代码，当我尝试保存10个以上学生的成绩时，在从表格中读取标记，名称和准入的行上出现未定义的偏移错误，输入表格包含在表格行中， 对于10条或更少的记录，它可以保存，但10条以上的记录将失败

 if(isset($_POST['submit']))
  {

      //maxipain & kenny @codei

      for($i=0;$i<$_POST['count'];$i++)
      {
          $mark[$i]=$obj->con->real_escape_string(htmlentities($_POST['cat1'][$i]));
          $names[$i]=$obj->con->real_escape_string(htmlentities($_POST['names'][$i]));
          $admission[$i]=$obj->con->real_escape_string(htmlentities($_POST['admission'][$i]));
          $key[$i]=$year . $term . $subject . $_POST['admission'][$i];

          if($mark[$i]>0)
          {
              if($mark[$i]<=30 && is_numeric($mark[$i]))
              {
                  /*
                   * if marks are consistent,
                    check if previous results
                    exist
                  */

                  $where=array("admission"=>$admission[$i],"period"=>$period,"subject"=>$subject);
                  $fetch_results=$obj->fetch_records("results",$where);

                  //if results for selected subject exist in results table
                  if($fetch_results)
                  {

                      foreach($fetch_results as $row)
                      {
                          $total[$i] = $row['total'] + $mark[$i];

                          //getting grade for updating
                          $sql = "SELECT * FROM grading_system WHERE upper_limit>=floor($total[$i]) AND lower_limit<=floor($total[$i])";
                          $execute = mysqli_query($obj->con, $sql);

                          if ($execute) {

                              while ($get_grades = mysqli_fetch_assoc($execute)) {
                                  $grade[$i] = $get_grades['grade'];
                                  $points[$i] = $get_grades['points'];
                                  $remarks[$i] = $get_grades['remarks'];
                              }

                              //updating data to subject results table


                              $data = array(

                                  "cat" => $mark[$i],
                                  "total" => $total[$i],
                                  "grade" => $grade[$i],
                                  "points" => $points[$i],
                                  "remarks" => $remarks[$i],
                                  "cat_entered" => '1'


                              );