help about file uploading

[ali]

I am writing a script which uploads file to a specific directory; I am
using javascript to handle client side exceptions and php script which
actually performs file uploading.

Php scripts gets session id, appends it with uploadpath and creates
new directory as uploadPath/sessionId. After that it uploads file in
uploadPath/sessionId/welcome.jpg.


It works fine locally but when I uploaded my site to server it is not
able to create directory rather creates only file i.e
uploadPath/welcome.jpg and misses out session id.

I have checked rights, I have rights of folder creation,


Any idea ??