PromptSelectionResult not working correctly

[ursan]

hi guys

my app code in following. i want to find blockreference in between two points. when i zoom extent working correct. bu i change zoom in autocad result incorrect. i added screenshot. i use SelectCrossingWindow or SelectWindow finally same.

 

 

     Public Sub FindBlockInFrame(frame As Extents3d)

           Dim tvs As TypedValue() = New TypedValue() _
           {
               New TypedValue(DxfCode.Start, "INSERT"),
               New TypedValue(DxfCode.BlockName, "myblock")
           }

           Dim filter As New SelectionFilter(tvs)
           Dim selection As PromptSelectionResult = ed.SelectCrossingWindow(frame.MinPoint, frame.MaxPoint, filter)
           'Dim selection As PromptSelectionResult = ed.SelectWindow(frame.MinPoint, frame.MaxPoint, filter)

           If selection.Status <> PromptStatus.OK Then
               Return
           End If

           Using tr As Transaction = db.TransactionManager.StartTransaction()

               Dim list As New List(Of BlockReference)

               For Each id As ObjectId In selection.Value.GetObjectIds()

                   Dim block As BlockReference = DirectCast(tr.GetObject(id, OpenMode.ForRead), BlockReference)
                   list.Add(block)
               Next

               ed.WriteMessage(vbLf & "block count in frmae  {0})", list.Count)

               tr.Commit()
           End Using
       End Sub

 

 

zoom extent:

 

zoom out:

 

zoom out,zoom out,zoom out: