Unable to refer to controls in code

Hello,

I'm trying to develop a test application along the lines of the 'Patterns in Action 4.5' application. I've created all the requisite layers and am now working working on the Presentation Layer, which is where I'm running into problems.

I've added a webform using the Site.Master template and am attempting to fill a gridview control using a textbox as a filter and a command button to bind the gridview. So I place textbox, command button and gridview controls on my webpage, name them and then start to write the required code.

However, I'm unable to refer to any of the controls using either, for example, 'textboxname' or 'me.textboxname'. The error that's given is that the control 'textboxname' is not a member of Namespace 'myNamespace'.

I've added a webform to my project without using the Site.Master as a template and everything is to be OK - I add controls and can refer to them in code modules etc.

So why should creating the Site.Master to create a webform cause this problem? Thanks for any help.