Cell Type Constants Returns Wrong Order

I'd like to add items on a UserForm1 ComboBoxes in the correct order but I can't. That's because with the code below, in ComboBox6P1 the items are added with mixed order:

For Each thing In .Range("AC6", .Range("AC65536").End(xlUp)).SpecialCells(xlCellTypeConstants)
If Trim(ComboBox4P1.Text) = thing.Value Then
For Each aNew In .Range("AD6", .Range("AD65536").End(xlToRight)).SpecialCells(xlCellTypeConstants)
If aNew.Row = thing.Row Then
ComboBox6P1.AddItem aNew.Value
End If
Next
Exit For
End If
Next

I should add items in ComboBox6P1 in order -> AD6, AE6, AF6, AG6, AH6, the rest are empty cells. Instead of it adds AF6, AG6, AH6, AD6, AE6. When I change .SpecialCells(xlCellTypeConstants) to .SpecialCells(xlCellTypeVisible ) it adds it in the correct order but with another 200 emtpy cells in the ComboBox6P1. The format of the cells is General.