How to re-display textbox with change combo box selection

Anyone help me... how to re-visable/display the available parat???boxs (default visible=false) with re-change combo box selection as following code:

Private Sub SystemComboBox_Change()
Dim choice As Integer
choice = SystemComboBox.ListIndex
CheckParameterBox
Range("Tile") = Sheets("code").Range("A" & choice + 3)
end sub

Sub CheckParameterBox()
If Range("test_type") = "test1" Or _
    Range("test_type") = "test1a" Then
    paratStartBox1.Visible = True
    paratStopBox1.Visible = True
elseIf Range("test_type") = "test2" Or _
    Range("test_type") = "test2a" Then
    paratStartBox1.Visible = True
    paratStopBox1.Visible = True
    paratStartBox2.Visible = True
    paratStopBox2.Visible = True
elseIf Range("test_type") = "test3" Or _
    Range("test_type") = "test3a" Then
    paratStartBox1.Visible = True
    paratStopBox1.Visible = True
    paratStartBox2.Visible = True
    paratStopBox2.Visible = True
    paratStartBox3.Visible = True
    paratStopBox3.Visible = True
elseIf Range("test_type") = "test4" Then
    paratStartBox1.Visible = True
    paratStopBox1.Visible = True
    paratStartBox2.Visible = True
    paratStopBox2.Visible = True
    paratStartBox3.Visible = True
    paratStopBox3.Visible = True
    paratStartBox4.Visible = True
    paratStopBox4.Visible = True
End If
End Sub