Access Violetion on TCnFontPropEditor

Hello,
[6FAA3408]{vcl290.bpl  } Vcl.Graphics.TFont.GetStyle (Line 2888, "Vcl.Graphics.pas" + 0) + $0
[613E77C4]{CnWizards_D120A.DLL} CnDesignPropEditors.TCnFontPropEditor.GetValue (Line 662, "CnDesignPropEditors.pas" + 1) + $7

Could you give more details about how to reproduce this problem?