Also to aid in the VBA writing, I am including the comprehensive code where the in-executable code is nested in:
Code:
Private Sub btnFilterCert_Click() If IsNull(Me.LstAccredStatus) Then
Me.FilterOn = False
Else
Me.Filter = "[AccredStatus] = " & Me.LstAccredStatus & ""
Me.FilterOn = True
TotalCerts.SetFocus
TotalCerts.ControlSource = "IIf(Forms!frmCertifyingAgentsDirectory.FilterOn=true,IIf(IsNull([LstAccredStatus]), ""# of total certifiers"", ""# of total "" & [LstAccredStatus].[Column](1) & "" certifiers""),""# of total certifiers"")"
LstAccredStatus.SetFocus
End If
End Sub