代理后面的curl post文件返回错误

我正在尝试将图像文件发布到服务器。最初，我在家里测试了我的脚本，没有代理，效果很好。但当我在大学里使用同样的脚本时，却出现了一些错误。上传图像的功能如下

function upload($filepath,$dir)
{
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_HEADER, 0);
    curl_setopt($ch, CURLOPT_VERBOSE, 0);
    curl_setopt($ch, CURLOPT_PROXY, 'localhost:7777');
    curl_setopt($ch, CURLOPT_PROXYUSERPWD, 'ae07b026:kpack');
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_USERAGENT, "Mozilla/4.0 (compatible;)");
    curl_setopt($ch, CURLOPT_POST, true);
    curl_setopt($ch, CURLOPT_URL, 'http://finalytics.in/sites/scrap/uploader.php' );
    $post_array = array(
        "my_file"=>"@".$filepath,
        "upload"=>"Upload",
        "dir"=>$dir
    );
    print_r($post_array);
    curl_setopt($ch, CURLOPT_POSTFIELDS, $post_array); 
    $response = curl_exec($ch);
    echo $response; 
}

uploader.php是一个普通的文件，只保存图像。

我得到的错误就像这个

        ERROR
    The requested URL could not be retrieved
While trying to process the request:
    POST /sites/scrap/uploader.php HTTP/1.1
    Proxy-Authorization: Basic YWUwN2IwMjY6a3BhY2s=
    User-Agent: Mozilla/4.0 (compatible;)
    Host: finalytics.in
    Accept: */*
    Proxy-Connection: Keep-Alive
    Content-Length: 87022
    Expect: 100-continue
    Content-Type: multipart/form-data; boundary=----------------------------07ae68105e71

The following error was encountered:
    Invalid Request 
Some aspect of the HTTP Request is invalid. Possible problems:
    Missing or unknown request method
    Missing URL
    Missing HTTP Identifier (HTTP/1.0)
    Request is too large
    Content-Length missing for POST or PUT requests
    Illegal character in hostname; underscores are not allowed 
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