Ok, so, my visual studio is broken. I say this NOT prematurely, as it was my first response to see where I had messed up in my code. When I add controls to the page I can\'t
I observed this happens because of missing .designer.cs file. Following fixed this issue in my case (basically I had these files copied from VS 2005 web project to VS 2010 project): Right Click on .aspx file and select menu "Convert to Web site", this will create .designer.cs file and then it should work file.