How to send multiple images into REST API - php

Question

I'm taking multiple documents of candidate from database, put it into one array and sending this array and some other additional information to the REST API. Then it's throwing an exception FILE Type NOT Support. When sending single image it works properly.
foreach($a_files as $a_file)
{
$file_name_with_full_path=$a_file->uploaded_path.$a_file->document_name;
$mime_type=mime_content_type($file_name_with_full_path);
$cFile[] = '#'.realpath($file_name_with_full_path).';type='.$mime_type.';';
}
Sending this information through REST API. My post data is like:
$post= array('level' => "level",
'nameOfInstitute' => "nameOfInstitute",
'nameAsPerDocument' => "nameAsPerDocument",
'issueDate' => "issueDate",
'registrationNumber' => "registrationNumber",
'yearOfPassing' =>"yearofpassing",
'degree' =>"degree",
'fieldOfStudy' =>"fieldofstudy",
'grade' =>"grade",
'nameOfBoardUniversity'=>"university",
'file' =>$cFile
);
$ch = curl_init();
curl_setopt($ch, CURLOPT_HTTPHEADER, array('Content-Type: multipart/form-data'));
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 0);
curl_setopt($ch, CURLOPT_SAFE_UPLOAD, false);
curl_setopt($ch, CURLOPT_USERPWD, $val);
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 0);
curl_setopt($ch, CURLOPT_URL,$target_url);
curl_setopt($ch, CURLOPT_POST,1);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, $post);
$response = curl_exec ($ch);
$err = curl_error($ch);
curl_close($ch);
It's throwing an exception file type not supported. But when sending single file, it's working fine (without loop). What is the problem in above code when sending multiple files in the API. Please help me out from this problem.