title: isEmpty() Always returning false
body: <p>I have a VBA function called getYear that is initialized as follows :</p>
  
  <p><code>Public Function getYear(ByVal year As Date, Optional ByVal month As Date) As Long</code></p>
  
  <p>Then, inside the function I have :</p>
  
  <p><code>msg = MsgBox(IsEmpty(month), vbOKOnly)</code> So I know whether or not the month has been input in the function.</p>
  
  <p>The only thing is whether I have a function call such as : <code>getYear(currentYear)</code> or <code>getYear(currentYear, currentMonth)</code> <code>isEmpty</code> is always returning <code>False</code> </p>
  
  <p>If I am understanding this correctly when I call <code>getYear(currentYear)</code> <code>isEmpty()</code> should return <code>True</code>, but it is not...</p>
  
  <p>I gather that is from my function initialization, but I don't know what else to do.</p>
  
  <p>Any help is appreciated!</p>