Why my macro doesn't delete all the rows (VBA)

Question

i have this macro it is supposed to delete all the cells that doesnt have a background set to them, but when I execute the macro if two or more contiguous cells doesnt have

Answer 1

Sub Macro1()
    Dim a As Range, x As Long

    Set a = Hoja1.Range("A1:A12")

    For x = a.cells.count to 1 Step -1
        with a.cells(x)
            if .Interior.ColorIndex = xlNone Then .EntireRow.Delete
        End With
    Next x
End Sub