title: Value of type 'List (of Strings) cannot be converted to String()
body: <p>Whenever I use this code in a private solution it works perfectly, but whenever I try to implement it on my main program I get the above error. Any idea on what could block the proper usage of this over the two solutions?</p>
  <pre><code>Private Sub GameID_Validating(sender As Object, e As CancelEventArgs) Handles GameID.Validating
             LoadAlreadyUsed(dataFile)
      If ActiveControl.Equals(sender) Then
          Exit Sub
      End If
  
      Dim tb = DirectCast(sender, TextBox)
      Dim txt = GameID.Text
      If Not txt = &quot;&quot; Then
          Dim res As String = Replace(txt, Space(1), Space(0))
          txt = res
          GameID.Text = res
          If alreadyUsed.Contains(txt, StringComparer.CurrentCultureIgnoreCase) Then
              'MessageBox.Show(&quot;This code has already been used.&quot;, &quot;Cheat attempt violation&quot;, MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
              GameID.BackColor = Color.Red
              GameID.Select()
          Else
              GameID.BackColor = Color.LimeGreen
              alreadyUsed.Add(txt)
      → → → →   File.WriteAllLines(dataFile, alreadyUsed)
          End If
      End If
      If alreadyUsed.Count &gt; 30 Then
          Do Until alreadyUsed.Count = 30
              alreadyUsed.RemoveAt(2)
          Loop
      End If
  End Sub
  </code></pre>