not retaining value of fileupload control in asp wizard control

Hi, I am developing a web application in asp.net and c#. I'm using an asp wizard control. there is  6 wizard steps in my wizard. In each phase im using many controls, so that many postback is done during execution. I am using a asp fileupload control in second wizard step. My problem is that the value selected using fileupload control is not getting when i click wizard finsh button in the final step. values acquired using all other controls are available ...