title: expression does not produce a value when calling a sub
body: <p>i want to call this public sub hungrys(gutom as string) from my zooanimal class to my form1.vb. for reference, please refer to my code. 
  i always get an error "expression does not produce a value" in my Textbox10.text = za.hungrys(gutom as string)</p>
  
  <pre><code>Public Class ZooAnimal
  
  Public Sub New()
  hungry = isHungry()
  
  Public Function isHungry() As Boolean
      If age &gt; 0 Then
          hungry = True
      End If
      If age &lt;= 0 Then
          hungry = False
      End If
      Return hungry
  End Function
  
   Public Sub hungrys(ByRef gutom As String)
      If hungry = True Then
          gutom = "The zoo animal is hungry"
      End If
      If hungry = False Then
          gutom = "The zoo animal is not hungry "
      End If
  End Sub
  
  Public Class Form1
  Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
  
  Dim za As New ZooAnimal
  Dim gutom As String = ""
  
  TextBox10.Text = za.hungrys(gutom)
  </code></pre>