Java applet clearing session variables?

It seems that our java applet is clearing our php session variables. I have an html form that saves user information as session variables. These session variables are used to create folders, where uploaded files can be saved. I've tested my php script that uses the session variables to create a folder and then moves uploaded files to that folder with a traditional html upload form. However, when I use a java applet in place of the traditional html form the php script does not create the folder, and thus it obviously cannot move the uploaded files. I've tested the applet and it does successfully upload files to the server. When I printed the session array variable after using the applet, I noticed the session array was empty. Does anyone know why this the applet clears the session variables? Or how to stop/work around it so I can use the applet and the php script? Thanks, Dan