AJAX UpdatePanel Problem: Update() Method not working (using Masterpages)

Question

Hello all, new to the site. I have been researching this problem for a while and am still finding it troubling. I am using an C#.NET 3.0, AJAX UpdatePanel in a page using Masterpages. What I want to do is have the user click a button which processes orders. As the orders process, I want each order processing result message to display on the screen upon its completion. However, I am having trouble getting the UpdatePanel to refresh when not triggered by a control (i.e. using the Update() method). What is happening is that all the result messages display at once, after the last order has finished processing. I read that sometimes in certain browsers the problem can be related to partial page rendering not being supported, but I explicitly set this to true and still have the same problem. Any advice? Could it be related to the masterpage that is being used? Are there other ways to manually refresh the update panel? Thanks! Callie EDIT: I guess a better question would be: is there a way to dynamically change the text of a label inside an ASP:UpdateProgress tag while something on the page is being processed?