To run a page in Debug mode you will have to choose Debug –> Start Debugging or just press F5.
Debugging support is not enabled by default and if you have not run the debugger before on this web site, you will need to configure it. This is internally driven by a setting in Web.cong file. By default, debug is set to ”false” in compilation section of web.config file.
If you click OK, Visual Web Developer will modify web.config to show debug=”true” as shown below.
<compilation debug="true" strict="false" explicit="true">
SDET, Web Development Tools