尝试使用PHP从远程位置复制图像时出现问题

I'm trying to copy an image from a remote location. I created a function that takes in the file name ($fname) and the path of the image ($remote_path). Currently I'm running PHP 5.3.28 with the following code:

function copy_remote_image($fname, $remote_path){

    $thumbWidth = 612;
    $folder = 'uploads/photos/';

    $img = imagecreatefromjpeg( $remote_path );

    if($img){
        $width = imagesx( $img );
        $height = imagesy( $img );
        // calculate thumbnail size
        $new_width = $thumbWidth;
        $new_height = floor( $height * ( $thumbWidth / $width ) );
        // create a new temporary image
        $tmp_img = imagecreatetruecolor( $new_width, $new_height );
        // copy and resize old image into new image 
        imagecopyresampled( $tmp_img, $img, 0, 0, 0, 0, $new_width, $new_height, $width, $height );
        // save thumbnail into a file
        imagejpeg( $tmp_img, $folder.$fname,70 );
        imagedestroy($tmp_img);
        return true;
    }else{
        return false;
    }   
}

As of now the image is not copying and when I use var_dump on $img i get: resource(25) of type (gd)