Combo box on a user form:using unique range

Use this code in userform with initialize event

Private Sub UserForm_Initialize()

Dim a  As Integer

Dim vlu, ele

a = Application.CountA(Range("A:A"))

''''initializing1

Me.ComboBox1.Clear

        With Sheets("sheet1").Range("e2:e" & a)

            vlu = .Value

        End With

        With CreateObject("scripting.dictionary")

            .comparemode = 1

            For Each element In vlu

                If Not .exists(element) Then .Add element, Nothing

            Next

            If .Count Then Me.ComboBox1.List = Application.Transpose(.keys)

        End With

        Set element = Nothing

        Set vlu = Nothing