Textbox Update by If and Statement

Afternoon

I'm not an experienced coder however I have been trying to have a textbox update, when the user toggles two combo boxes. However, it fails and no matter what scenarios I add to VBA if has an error.

Would you be able to point me in the right direction?

Scenario, Textbox Updates when Both Combo Boxes are > 0, if both conditions are not met then returns ""

The Codes I have tried is:

Private Sub CB_UsageFreqScore_Change()

If CB_ImpactScore.Value > 0 And CB_UsageFreqScore Then
   TB_UsageScore.Value = CB_UsageFreqScore.Value * CB_ImpactScore.Value

   Else
   TB_UsageScore.Value = ""

End If
End Sub

Private Sub CB_ImpactScore_Change()

If CB_ImpactScore.Value > 0 And CB_UsageFreqScore Then
   TB_UsageScore.Value = CB_UsageFreqScore.Value * CB_ImpactScore.Value

   Else
   TB_UsageScore.Value = ""

End If
End Sub