If SelectionCount <> 0 Then
pTopologicalOperator = CType(WALL_Feature.Shape, ITopologicalOperator)
pTopologicalOperator.Simplify()
While OtherFea IsNot Nothing
Dim LayerName As String = OtherFea.Value(OtherFea.Fields.FindField("Layer")).ToString.ToUpper
If LayerName <> "WALL" Then
Dim oPolygon As IPolygon
oPolygon = OtherFea.ShapeCopy
oPolygon.SimplifyPreserveFromTo()
pTopologicalOperator = pTopologicalOperator.Difference(oPolygon) (here Exception from HRESULT: 0x80040215 )
End if