VBA Click Box not Updating Formula

[michaelg777]

I have the following code in my worksheet and it works when you check the box. However when the values in ranges C29 and B29 change, C18 and C19 do not update automatically. I have to uncheck the box and check it again for it to update? I would also like to add if checkbox3 = false then nothing (as in C18 and C19 are empty and anyone is free to input their own value). Thanks!

Private Sub CheckBox3_Click()
Application.ScreenUpdating = False
Application.Volatile
If CheckBox3 = True Then
Range("C18") = Range("B29")
Range("C19") = Range("C29")
Application.ScreenUpdating = True


End If



End Sub