wxTextEntryDialog assertion problem

Question

Hi guys! I am making a text entry dialog in wxWidgets, and I always get a assertion error. Code looks like this:

int CFrame::MenuSetAmbient(wxCommandEvent &event)
{ 
 wxTextEntryDialog dial(this, _T("Enter ambient light value..."), _T("Set value"), _T("0.5") ); 
 int result = dial->ShowModal();
 return result;  
}

Thanks for reply!