PHP CSVImporter

I had a script called CSVimporter V3 for PHP that I used to run on a website and it worked fine. A couple of years later I've now dug out the same script to use on another project, all works okay except the CSV files are being read as one long line, as opposed to header row and multiple lines.

Here is part of the script.

Any ideas why it would be being read as a long line?

<?php 

//  Reference session variable for short-hand
        $f = &$_SESSION['csv_file'];

        //  Open file - fp = file pointer
        if (!$fp = @fopen($f, 'r')) {

            error(L_ERROR_PREVIEW_NO_FILE);

        } else {

            //  Array to store each row to be inserted
            $batch = array();

            //  Row counter
            $rc = 0;

            //  Work out starting row
            switch ($_SESSION['csv_first_row']) {
                case 'data':
                    $start_row = 0;
                break;

                default:
                    $start_row = 1;
            }

            //  Get contents, while below preview limit and there's data to be read
            while ($data = fgetcsv($fp, 1024, delimiter_to_char($_SESSION['csv_delimiter']))) {

                if ($rc < $start_row) {

                    //  Incremement counter
                    $rc++;

                    //  Go to next loop
                    continue;

                } else {

                    //  Array to store data to be inputted
                    $values = array();

                    //  Loop data
                    for ($i = 0; $i < count($data); $i++) {

                        //  If data is wanted, put data into array
                        if (array_key_exists($i, $column_index)) {
                            $values[$column_index[$i]] = $data[$i];
                        }

                    }

                    //  Sort array into correct order by index
                    ksort($values);

                    //  Join values together and store in array
                    $batch[] = '("' . implode('", "', str_replace('"', '\"', $values)) . '","'.$accti.'","'.$impt.'")';

                }

            }


        }
            //  Close the file
            fclose($fp);