Hi:
I use to find the control from the following code and that is in the framework 2.0.
TextBox tb = (Textbox) PreviousPage.FindControl("Textbox1");
tb is the current refernce to the previous page control and the Textbox1 is the id of the previous page.
in the condition you must set PostBackURL (URL of that page in which u want to navigate the page) of the button control.
Kind Regards:
Ali Usman