How to upload files from one server to another using FTP - PHP?

Question

I m trying to upload a file from the Plesk server to the HostGator server using the FTP details I created in HostGator.

The code is from this query. Which I presume works fine. But for some reason, the file is not bing uploaded.

The code goes as:

<?php
    $ftp_server = "the.servername";
    $ftp_user_name = "the@username";
    $ftp_user_pass = "thepassword";
    $destination_file = " ";
    $source_file = $_FILES['files']['name']; 

    // set up basic connection
    $conn_id = ftp_connect($ftp_server);
    ftp_pasv($conn_id, true); 

    // login with username and password
    $login_result = ftp_login($conn_id, $ftp_user_name, $ftp_user_pass); 

    // check connection
    if ((!$conn_id) || (!$login_result)) { 
        echo "FTP connection has failed!";
        echo "Attempted to connect to $ftp_server for user $ftp_user_name"; 
        exit; 
    } else {
        echo "Connected to $ftp_server, for user $ftp_user_name";
    }

    // upload the file
    $upload = ftp_put($conn_id, $destination_file, $source_file, FTP_BINARY); 

    // check upload status
    if (!$upload) { 
    echo "FTP upload has failed!";
    } else {
    echo "Uploaded $source_file to $ftp_server as $destination_file";
    }

    // close the FTP stream 
    ftp_close($conn_id);
?>

Please note that the destination_file is empty as while I created the FTP logins in the HostGator, I clearly mentioned the folder the files have to upload. So I left this destination_file empty.

Now when I try to upload the error echo's as

Connected to ftp.vdofyfilex.com, for user files_from_vdofy@vdofyfilex.comFTP upload has failed!

As you can see, the connection was successful but the file was not uploading. could be because of destination_file is empty.

Things I have tried with $destination_file:

1. $destination_file = 'added the full domain with directory'
2. Added a sub folder as temp and $destination_file = 'temp/'
3. Added a sub folder as temp and $destination_file = 'full domain with directory + temp/'
4. $destination_file = ''

None of 'em worked.

Any help is greatly appreciated.