Can't Trigger a Macro When a ComboBox is Changed

I inserted a standard Excel combo box form control in a worksheet. I'm trying to trigger a macro when this value is changed, but I can't get Worksheet_Change(ByVal Target As Range) to recognize the action/change. I tried multiple things, and currently have;

Private Sub Worksheet_Change(ByVal Target As Range)
    If Not Intersect(Target, Me.DropDowns("DropDownSiteSelection")) Is Nothing Then
        BuildQQControlGroupTest
    End If
End Sub

But like I said the code isn't even being triggered when the box is changed. What am I doing wrong? Thanks!