Event Trigger Not Working

I am trying to call a Sub based on the value of a drop down list. I have created all of the individual subs for each of the different values in the drop down list and saved them in the Modules. I have run each of the Module subs and they work correctly. I created the following event trigger sub and placed it in Sheet1 under objects. When I change the values on the drop down list nothing happens. Any ideas?

Private Sub Worksheet_Budget_Prefill_Trigger(ByVal Target As Range)

    If Not Intersect(Target, Range("M12")) Is Nothing Then
        Select Case Range("M12")
            Case "Select": Budget_Prefill_NotSelected
            Case "Original": Budget_Prefill_Original
            Case "Budget Adjustment": Budget_Prefill_BudgetAdjustment
            Case "Change Order": Budget_Prefill_ChangeOrder
            Case "Final": Budget_Prefill_FianlAdjustment
        End Select
    End If
    
End Sub

Welcome to the foums!

Please take a look at the second of our forum rules regarding code tags, which you will need to add yourself in future. I will do it for you this time. Thanks!

That is not a valid event, unless you have declared your own event?

I meant that worksheet events have very specific names and signatures. For a worksheet_change event, which I suspect this needs to be, you have to call it Worksheet_Change:

Private Sub Worksheet_Change(ByVal Target As Range)

or it will not respond to changes on the worksheet.