Button within a dialog in a CTabCtrl don't work?

Hi all
I'm relatively new to MFC coding, so I hope you can help.
My problem is:
I have a dialog. Within this dialog is a CTabCtrl. This CTabCtrl has a dialog with it's own class. Within this dialog contains a button. Clicking on the button should bring up a AfxMessageBox("Test") but doesn't bring up anything. I tried setting a breakpoint on this line and it's never reached...

To reproduce the problem, do the following:
 - Create a new Dialog Based MFC AppWizard Project (I called it "Tester")
 - On the IDD_TESTER_DIALOG, place a CTabCtrl with the default name "IDC_TAB1"
 - In the Classwizard, for IDC_TAB1, Add a variable. Call it "m_Tabs" with Category "Control" and type "CTabCtrl"
 - Insert a new dialog with default name "IDD_DIALOG1", style="Child" and no title bar.
 - In "TesterDlg.h", go to the definition of m_Tabs. Under this line, put "CDialog   m_TestDlg" so it becomes:

     //{{AFX_DATA(CTesterDlg)
     enum { IDD = IDD_TESTER_DIALOG };
     CTabCtrl     m_Tabs;
     CDialog     m_TestDlg;
     //}}AFX_DATA

 - In "TesterDlg.cpp", in the CTesterDlg::OnInitDialog() section, add the following under the SetIcon lines:

     m_Tabs.InsertItem (0, "Test");
     m_TestDlg.Create (IDD_DIALOG1, &m_Tabs);
     m_TestDlg.ShowWindow (SW_SHOW);

 - Go to IDD_DIALOG1. Place a button with a default name of "IDC_BUTTON1"
 - Double click on the button. It will ask you to create a class. Create a new class named "CTheTester" with a Base Class "CDialog" and DialogID "IDD_DIALOG1".
 - Exit the Classwizard if you're still there
 - Double click on the button again. This time it will ask you to name the member function. Call it "OnButton1"
 - Within this function, put the line "AfxMessageBox ("Test!");"
 - Compile and run.

When you click the button we created, it doesn't work...Can anyone tell me where I went wrong? or if there's any lines I should add to rectify this?

The same thing happens when I put down a combo box and test to see when the contents change, so I think it may happen for any controls I put down.

Thanks for any help!