I'm working with ASP.net 3.5 and having a problem with adding an item to a List of a Structure in the ViewState.

I've declared the item to be added as New, but it complains when trying to insert into the viewstate object.

here's the code...

Code:
        Public Property QuestionsCorrect() As QuestionAnswer
            Get
                Return ViewState("QuestionsCorrect")
            End Get
            Set(ByVal value As QuestionAnswer)
                ViewState("QuestionsCorrect") = value
            End Set
        End Property
Code:
       Public Sub ProcessAnswers()
            Dim qA As New QABase
            Dim answerLetter As String = hidClickedAnswer.Value
            Select Case answerLetter
                Case "A"
                    If ActiveQuestionAnswer = 0 Then
                        qA.Correct = True
                    Else
                        qA.Correct = False
                    End If
                Case "B"
                    If ActiveQuestionAnswer = 1 Then
                        qA.Correct = True
                    Else
                        qA.Correct = False
                    End If
                Case "C"
                    If ActiveQuestionAnswer = 2 Then
                        qA.Correct = True
                    Else
                        qA.Correct = False
                    End If
                Case "D"
                    If ActiveQuestionAnswer = 3 Then
                        qA.Correct = True
                    Else
                        qA.Correct = False
                    End If
                Case "E"
                    If ActiveQuestionAnswer = 4 Then
                        qA.Correct = True
                    Else
                        qA.Correct = False
                    End If
            End Select
            qA.QuestionId = ActiveQuestion
            QuestionsCorrect.QuestionList.Add(qA)
            If ActiveQuestion < 10 Then
                ActiveQuestion = ActiveQuestion + 1
            End If
        End Sub
Here's the class for all that
Code:
<Serializable()> _
Public Class QuestionAnswer
    Private _QuestionList As New List(Of QABase)
    Public Property QuestionList() As List(Of QABase)
        Get
            Return _QuestionList
        End Get
        Set(ByVal value As List(Of QABase))
            _QuestionList = value
        End Set
    End Property
End Class

<Serializable()> _
    Public Class QABase
    Private _QuestionId As Integer
    Private _Correct As Boolean

    Public Property QuestionId()
        Get
            Return _QuestionId
        End Get
        Set(ByVal value)
            _QuestionId = value
        End Set
    End Property
    Public Property Correct()
        Get
            Return _Correct
        End Get
        Set(ByVal value)
            _Correct = value
        End Set
    End Property
End Class
i've been working on this for sometime and can't figure it out...any help is greatly appreciated