PHP取消链接删除不正确的文件名

I want to make a function to delete a file in my folder through php. I've written the code based on suggestion from here, but eventually it is not deleting the file I intended to remove. It's removing other file instead. Here's the code :

$file_name = $this->input->post('file_name'); //getting file name from view

$path_gse = realpath('file_upload/station_report/gse_serviceability/'.$file_name);
if(is_writable($path_gse)) {
    unlink($path_gse);
}

In $file_name variable I pass it from view with ajax, I've tested it and it did return the correct file name. I really have no idea why this function delete the file that I don't intended to remove.

UPDATE

Here's the files in folder before I delete,

Then I delete a row number 3 from html table,

It suppose to delete a file named crew_conden-1801-Local_Time ver download tgl 18 Jan 18, but here's what happened,

It deleted OTP Dashboard development file instead of crew_conden-1801-Local_Time ver download tgl 18 Jan 18