Linq Conversion Failure

[Richard]

The following VB function does not convert to C#
Private Function GetQuestions(orgId As Integer, personId As Integer) As IEnumerable(Of Question)

    Dim ds As DataSet = GetActualDataSet(orgId, personId)

    Dim dtQuestions As DataTable = ds.Tables("Questions")

    Dim dtAnswers As DataTable = ds.Tables("Answers")

    Dim childQuestions As DataTable = ds.Tables("AnswerChildQuestions")

    'Build all the questions

    Dim questions As IEnumerable(Of Question) =

        (From q In dtQuestions

         Group Join a In dtAnswers On q.Field(Of Integer)("question_type_id") Equals a.Field(Of Integer)("question_type_id") Into Group

         Select New Question With {.Id = q.Field(Of Integer)("question_type_id"),

                                   .SeqNum = q.Field(Of Integer)("sequence_no"),

                                   .IsChild = q.Field(Of Boolean)("isChildQuestion"),

                                   .EktronContentKey = q.Field(Of String)("ektron_content_key"),

                                   .Text = q.Field(Of String)("description"),

                                   .QuestionKindId = q.Field(Of Integer)("question_kind_type_id"),

                                   .Answers = (From a2 In Group

                                               Select New Answer With {.Id = a2.Field(Of Integer)("answer_type_id"),

                                                                       .SequenceNum = a2.Field(Of Integer)("sequence_no"),

                                                                       .EktronContentKey = a2.Field(Of String)("ektron_content_key"),

                                                                       .Text = a2.Field(Of String)("description"),

                                                                       .IsSelected = a2.Field(Of Boolean)("isSelected"),

                                                                       .ImageKey = If(q.Field(Of Integer)("question_type_id") = 2, "", If(.Id Mod 2 = 0, "heating-gas-modern.png", "heating-gas-condensing.png")),

                                                                       .ChildQuestionIds =

                                                                          (From r In childQuestions

                                                                           Where r.Field(Of Integer)("answer_type_id") = .Id

                                                                           Select r.Field(Of Integer)("question_type_id")).ToArray}).ToArray,

                                   .SelectedAnswerId = If(.QuestionKindId = 1,

                                                          (From a3 As Answer In .Answers

                                                           Where a3.IsSelected = True

                                                           Select a3.id ).singleOrdefault,

                                                          0),

                                   .SelectedAnswerIds =If(.QuestionKindId = 2,

                                                          (From a4 As Answer In .Answers

                                                           Where a4.IsSelected = True

                                                           Select a4.id).toArray,{})

                                  }

         )

    Return questions

End Function