DoModal() results in an abrupt close of my application

Hi there,

I am in the trouble of CPropertySheet's domodal which result in an
sudden close of my application. What I get confused is that this
happens when my application has another modal dialog open. If my
application has another modeless dialog open, the trouble is gone. I am
wondering if the existing modal dialog took sth. so that the
CPropertySheet dialog cannot go further with DoModal?

I stepped into the code and found that the failure started from the MFC
inside code as below. LockResource always returns null to me so that
exception is thown out.

CPropertyPage::PreProcessPageTemplate(PROPSHEETPAGE& psp, BOOL
bWizard)
  {
      const DLGTEMPLATE* pTemplate;
      if (psp.dwFlags & PSP_DLGINDIRECT)
      {
          pTemplate = psp.pResource;
      }
      else
      {
          HRSRC hResource = ::FindResource(psp.hInstance,
          psp.pszTemplate, RT_DIALOG);
          HGLOBAL hTemplate = LoadResource(psp.hInstance,
          hResource);
          pTemplate = (LPCDLGTEMPLATE)LockResource(hTemplate);
      }
      ASSERT(pTemplate != NULL); // < THIS IS THE LINE THAT ASSERTS

Any suggestions are welcome!

lvcha