title: Strange MsBuild Error (Everything builds fine in Visual Studio)
body: <p>First off, I tried a shorter version of the code for my stackoverflow question but that doesn't cause my compiler error. Also, I can't user the AspnetCompiler instead of MsBuild because I am building a solution of multiple websites and class libraries. My build server setup has been in place for years and I have never had any problems like this. I have a VB.Net Library that I use extensively with C#, in that library I have the following:</p>
  
  <pre><code>   Public Class PropertyParticipants
  
          Public Property Participants As List(Of Participant)
          Private _propertyId As Integer
  
          Public Sub New(propertyId As Integer)
              Participants = New List(Of Participant)()
              _propertyId = propertyId
  
              LoadParticipants()
          End Sub
    End Class
  
    Public Class Participant
  
      Public Property Role As ParticipantRole
      Public Property Type As ParticipantType
      Public Property FirstName As String
      Public Property LastName As String
      Public Property Password As String
      Public Property LoginId As String
      Public Property Initials As String
      Public Property UserId As Integer
  
  
      Public ReadOnly Property FullName() As String
          Get
              Return Me.FirstName &amp; " " &amp; Me.LastName
          End Get
      End Property
  
      Public Enum ParticipantRole
          Primary
          Party
          Pending
      End Enum
  
      Public Enum ParticipantType
          Seller
          Buyer
      End Enum
  
  End Class
  </code></pre>
  
  <p>Then in my c# code behind I have the following</p>
  
  <pre><code>        PropertyParticipants propPart = new PropertyParticipants(PropertyId);
  
          foreach (Participant part in propPart.Participants.Where(p =&gt; p.Role != Participant.ParticipantRole.Pending))
          {
             int userId = part.UserId; //this is fine
              string loginId = part.LoginId; //compiler error
       }
  </code></pre>
  
  <p>error CS1061: 'Participant' does not contain a definition for 'LoginId' and no extension method 'LoginId' accepting a first argument of type 'Participant' could be found (are you missing a using directive or an assembly reference?)</p>