Excel Scroll bar not initiating change event

I have set up a change event macro if cell a1 is changed, this then runs other macros to set displayed values in a chart.

At present I have linked a drop down list to update value A1. This triggers the change event and runs the macros.

However when I link cell A1 to a scroll bar, the cell value seems to change but the macros do not run.

How can I make the scroll bar change the value in A1 and trigger the change event macro?



Private Sub Worksheet_Change(ByVal Target As Range)
    If Not Intersect(Target, Range("a1")) Is Nothing Then graphselector2
End Sub

Sub graphselector2()
Dim choice
choice = Range("a1")

If choice = 1 Then
Run "aGraph1"

ElseIf choice = 2 Then
Run "aGraph2"

ElseIf choice = 3 Then
Run "aGraph3"

ElseIf choice = 4 Then
Run "aGraph4"

ElseIf choice = 5 Then
Run "aGraph5"

ElseIf choice = 6 Then
Run "aGraph6"

ElseIf choice = 7 Then
Run "aGraph7"

ElseIf choice = 8 Then
Run "aGraph8"

ElseIf choice = 9 Then
Run "aGraph9"

ElseIf choice = 10 Then
Run "aGraph10"

ElseIf choice = 11 Then
Run "aGraph11"

ElseIf choice = 12 Then
Run "aGraph12"




End If
End Sub
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