diff --git a/WebWindowComplex/Window.cs b/WebWindowComplex/Window.cs
index 1631b21..820d18e 100644
--- a/WebWindowComplex/Window.cs
+++ b/WebWindowComplex/Window.cs
@@ -1338,7 +1338,7 @@ namespace WebWindowComplex
             var iComp = StringComparison.InvariantCultureIgnoreCase;
             var rawList = m_HardwareCompleteList
                             .Where(x => x.Id == "000000" ||
-                                    (x.FamilyName.Equals(s_SelFamilyHW, iComp) && x.SashQty == nSashQty && x.Shape.Equals(sSashShape, iComp) && x.OpeningType.Equals(sOpeningType, iComp))
+                                    (s_SelFamilyHW != null && x.FamilyName.Equals(s_SelFamilyHW, iComp) && x.SashQty == nSashQty && x.Shape.Equals(sSashShape, iComp) && x.OpeningType.Equals(sOpeningType, iComp))
                              )
                             .ToList();
             if (rawList != null && rawList.Count > 0)