Usage of SetDlgItemText on Property pages globally

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MFC

Hello All,
In my MFC application, I've created the two tabbed control ( Tab1 & Tab2 ) using CPropertyPage & CPropertySheet. In Tab1 am having a static variable (IDC_SELL) & during runtime i need to change the label of the variable. My snipnet code looks like this:

UINT Thread(LPVOID lParam)
{
  //SampleApp --> Current MFC Application window.
  HWND hWnd = ::FindWindow(0,"SampleApp");

  while(1)
  {
    // Other stuffs ...
   
    ::SetDlgItemText(hWnd,IDC_SELL,"Hello");

  }
   return(1);
}

void CTab1Dlg :: OnButtonOK()
{
  AfxBeginThread(Thread,0);
}

With this code, the label IDC_SELL doesn't change to Hello. But when i code like this:

void CTab1Dlg :: OnButtonOk()
{
 SetDlgItemText(IDC_SELL,"Hello");
}

This works pretty well... I tried to create a thread in class like this:

//CTab1Dlg.h
class CTab1Dlg : public CPropertyPage
{
public:
  static UINT Thread(LPVOID lParam);
}
//CTablDlg.cpp
UINT CTab1Dlg :: Thread(LPVOID lParam)
{
while(1)
  {
    // Other stuffs ...
SetDlgItemText(IDC_SELL,"Hello"); // Here SetDlgItemText Crashes stating that m_hWnd is NULL.
  }
   return(1);
}

Please, Can anyone suggest me how to use SetDlgItemText globally in PropertyPages.

Thank you All.