asp.net textbox doesn’t populate after postback

I am using ASP.NET and C# couple text boxes to calculate results entered. Textbox2 has a value entered and on button click Textbox1 gets populated. This works fine the first time I enter the value. But the second time I change the value in Textbox2, I see that the value is being assigned to Textbox1 while debugging on Button click, but doesn’t show up on the screen. I have many other controls and a master page. The textboxes are within an update panel.

Changing connection string dynamically

I have a scenario where i am getting dynamically generated databases. I want to create a connection string for each database. So only initial catalog parameter will be changing. Other parameters i ll get it from web config file. It is already having all entries of connection string. I want to change only initial catalog part dynamically based on database created.