Multiple update panel on same page.Fileupload looses value on button click event
I am working on web application.I have webform having following structure. First update panel have fileupload control,checkbox and textbox and made mode to conditional.So fileupload control does not loose value on second update panel event occure like dopdownlist selected index change.On checkchange event of checkbox,textbox become invisible and fileupload control become visible and vice versa. Second update panel have dropdownlist along with one panel which contain textbox.Onselected index change of dropdownlist,panel get visible(textbox get visible).After 2 update panel, one calendar control and one button control.I want to save and read the file from button control event.But on onclick event of button,fileupload control loose the value>how to handle this?// Update panel 1 start
// textox control
// checkbox conrol
// fileupload control
// update panel 1 end
// Update panel 2 start
// dropdownlist with selected index change event
// On selected index change textbox get visible
// update panel 2 end
// Calender control
// Generate button