Multipart/form-data is missed by php-script

[Schmidt]

I want to write my own perl module for sending multipart/form-data to a website. In common, I write a scalar string, that consists all data to send to a server. It's look like

sub __prepareContent {
my $Instance = shift;

    my $hdrs_as_string;

    $hdrs_as_string = "POST ".$Instance->{requestPath}." HTTP/1.1
Host: ".$Instance->{host}."
User-Agent: PostMultipart_Simple ver-$VERSION
Accept: text/plain
Accept-Language: en-us
Accept-Charset: utf-8
Content-Type: multipart/form-data; boundary=$boundary
Content-Length:";

my $content = "\r\n--$boundary\r\nContent-Disposition: form-data; name=\"sel\"\r\n\r\n1\r\n--$boundary\r\nContent-Disposition: form-data; name=\"txt\"\r\n\r\n322133text\r\n--$boundary\r\nContent-Disposition: form-data; name=\"Upload\"\r\n\r\nUpload\r\n--$boundary".'--';

    $Instance->{length} = length $content;

    $Instance->{contentReady} = $hdrs_as_string.$Instance->{length}."\r\n".$content."\r\n\r\n";

    print $Instance->{contentReady};

    return $Instance;

as you can ses, an $Instance is a hash refrerence, which stores parsed URL and host. My php-script just displays a POST-data:

<?php
if($_REQUEST['upload']) { echo $_REQUEST['upload']; }
if($_REQUEST['txt']) { echo $_REQUEST['txt']; }
if($_REQUEST['sel']) { echo $_REQUEST['sel']; }
?>


<form action="<?php echo $_SERVER['PHP_SELF'];?>" method="POST" enctype="multipart/form-data">

<select name="sel">
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
</select>
<input type="text" name="txt"><br>
<input type="submit" value="Upload" name="upload">
</form>

( there must be file upload too, but I leave it away for easiest debugging ). When I use a web browser, It's all right - data passed well. But when I use my perl script (just sending prepared data to opened socket), I get php warnings "Undefined index ..." and empty $_REQUEST (but no any http or php errors more). What can be wrong?...