Automapper：无法转换类型为'System.Data.Entity.Infrastructure.DbQuery`1 [DataObjects.BookEntity]'的对象以键入'DataObjects.BookEntity

Question

请参阅以下代码：

Public Function GetBook(ByVal ISBN As Integer) As Book Implements IBookDAO.GetBook
        Using context = New LibraryDBEntities()
            'Dim bookDetails = context.BookEntities.Where(Function(b) b.ISBN = ISBN)
            Dim bookDetails = context.BookEntities.Where(Function(b) b.ISBN = ISBN)

            Dim details = Mapper.Map(Of BookEntity, Book)(bookDetails)
            Return details
        End Using
    End Function

我得到的错误是：“{”无法将类型为'System.Data.Entity.Infrastructure.DbQuery`1 [DataObjects.BookEntity]'的对象强制转换为'DataObjects.BookEntity'。“}”我是什么做错了？