Php problem in server and not in wamp

I made a gallery image manager with flash and php.

What it do is when uploading,

the php file retrieves the image and uploads into images folder.
then it creates a thumbnail of the uploaded image and puts it in another folder.
then it saves the name of the image in an XML file.

and when deleting,

it deletes the thumbnail image. and removes the item from XML file.

These all are working perfectly in WampServer. But when I uploaded into a server, it is not working.
Nothing, works no uploading, thumbing editing. And even I can’t delete the image.

The code for delete and upload are two php scripts.