TAB not being responded to in modeless

I am working on a program in which I am opening a popup window from a property sheet. The popup window itself opens a modeless dialog box which contains many text edit boxes. While the edit boxes seem to respond normally to most input, TABs will not move focus from one to the next as they should. The TABs work fine within the property sheets. I also do not seem to be able to trap any kind of key down commands.

The message loop in the main window routine has been modified to check if the modeless dialog box is active and if so reroute the message, but it doesn't seem to work. The functions for the popup window & modeless dialog box responded to TABs okay when they were in a test program, but the instant I started calling them from a property sheet routine, they stopped working.

The main message loop is as follows:
  while (GetMessage(&message, NULL, NULL, NULL))
  {
    if (!IsWindow(hwndModeless) ||!IsDialogMessage(hwndModeless, &message))
    {
      TranslateMessage(&message);
      DispatchMessage(&message);
    }
  }

If anyone has any suggestions on where my trouble spots might be, I would appreciate it.

Thanks in advance,

Bill