Dependent ComboBox in excel vba

Option Explicit

Private Sub ComboBox1_Change()

Me.ComboBox2.Clear

' set worksheet

Dim sh As Worksheet

Set sh = Sheets("Clients")

'declare variable

Dim i As Long

For i = 2 To sh.Range("A10000").End(xlUp).Row

If sh.Cells(i, 1) = Me.ComboBox1.Value Then

If Application.WorksheetFunction.CountIf(sh.Range("B2", "B" & i), sh.Cells(i, 2)) = 1 Then

Me.ComboBox2.AddItem sh.Cells(i, 2)

End If

End If

Next i

End Sub

Private Sub ComboBox2_Change()

Me.ComboBox3.Clear

' set worksheet

Dim sh As Worksheet

Set sh = Sheets("Clients")

'declare variable

Dim i As Long

For i = 2 To sh.Range("A10000").End(xlUp).Row

If sh.Cells(i, 2) = Me.ComboBox2.Value Then

Me.ComboBox3.AddItem sh.Cells(i, 3)

End If

Next i

End Sub

Private Sub UserForm_Click()

End Sub

Private Sub UserForm_Initialize()

' set worksheet

Dim sh As Worksheet

Set sh = Sheets("Clients")

'declare variable

Dim i As Long

For i = 2 To sh.Range("A10000").End(xlUp).Row

If Application.WorksheetFunction.CountIf(sh.Range("A2", "A" & i), sh.Cells(i, 1)) = 1 Then

Me.ComboBox1.AddItem sh.Cells(i, 1)

End If

Next i

End Sub