Audit trail of changees in values in specific columns

[Spoursy]

Ive watched the following video to create an audit trail

The code Im using is

Option Explicit
	Dim wsLOE As Worksheet, wsTrail As Worksheet
	Dim PreviousValue As Variant
	Private Sub Worksheet_Change(ByVal Target As Range)
	Set wsTrail = ThisWorkbook.Worksheets("Trail")
	If Target.Column = 3 Or Target.Column = 4 Then
	If Target.Value <> PreviousValue Then
	Call Log_Change(Target)
	End If
	End If
	End Sub
	Private Sub Log_Change(ByVal Cell_Target As Range)
	Dim RowInsertion As Long
	RowInsertion = wsTrail.Cells(Rows.Count, "A").End(xlUp).Row + 1
	wsTrail.Cells(RowInsertion, "A").Value = _
	Application.UserName & " changed cell " & Cell_Target.Address _
	& " from " & PreviousValue & " to " & Cell_Target.Value _
	& " on LOE worksheet"
	End Sub
	Private Sub Worksheet_SelectionChange(ByVal Target As Range)
	PreviousValue = Target.Value
	End Sub
	Private Sub Worksheet_Deactivate()
	Set wsLOE = Nothing
	Set wsTrail = Nothing
	End Sub

but I am getting a yellow hightlight at
RowInsertion = wsTrail.Cells(Rows.Count, "A").End(xlUp).Row + 1

any ideas on a fix to this?