User control (with multiple controls inside) added at design time, loosing values after postback

I have a user control, which is made up of some standard controls like text box, checkedlistbox, etc.  I am adding this during the design of the webpage. In the ascx page, I am creating these controls dynamically in Page_Init (always, without caring for postback)   But, the controls values are lost during post back.  The funny thing is that, it shows the new value entered by user, but  it holds the old value internally.