Kusaba stuff

I want to try something with kusabaX, I'm not familiar with web shit though.  I get a 500 internal server error trying some stuff with nc XXXXX 80 < post. What could the reason be? Here's the post data:

POST /board.php HTTP/1.1
Host: XXXXXX
User-Agent: XXXXXX
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip,deflate
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive: 115
Connection: keep-alive
Referer: XXXXX
Cookie: postpassword=XXXXXXX; PHPSESSID=26ca7d892721b2dad0f6c0b219e741c8
Content-Type: multipart/form-data; boundary=---------------------------16758665283689329972092157694
Content-Length: XXXXX

-----------------------------16758665283689329972092157694
Content-Disposition: form-data; name="board"

XXXXXX
-----------------------------16758665283689329972092157694
Content-Disposition: form-data; name="replythread"

XXXXXX
-----------------------------16758665283689329972092157694
Content-Disposition: form-data; name="MAX_FILE_SIZE"

XXXXXX
-----------------------------16758665283689329972092157694
Content-Disposition: form-data; name="email"


-----------------------------16758665283689329972092157694
Content-Disposition: form-data; name="name"


-----------------------------16758665283689329972092157694
Content-Disposition: form-data; name="em"

-----------------------------16758665283689329972092157694
Content-Disposition: form-data; name="subject"


-----------------------------16758665283689329972092157694
Content-Disposition: form-data; name="message"
(message data here)

-----------------------------16758665283689329972092157694
Content-Disposition: form-data; name="imagefile"; filename=""
Content-Type: application/octet-stream


-----------------------------16758665283689329972092157694
Content-Disposition: form-data; name="postpassword"

XXXXXXX
-----------------------------16758665283689329972092157694--

I gathered this from a packet analyzer session, while posting to the board with my browser. I supposed it'd be enough to replicate the request to the board, but it's not (thus teh 500 internal error). Is it the PHPSESSID variable? I'm not going to spam, but I'm doing this for evil reasons nonetheless.

Have you considered using --upload-file to upload your file?