DB4o保存数据出现异常，有人知道吗？？？？

将数据保存到本地数据库失败：Db4objects.Db4o.Ext.Db4oException: 'db4o ServerSocket FILE: D:\DB4o.yap  PORT:0' is closed. close() was called or open() failed.
   在 Db4objects.Db4o.Internal.Exceptions4.ThrowRuntimeException(Int32 code, String msg, Exception cause, Boolean doLog)
   在 Db4objects.Db4o.Internal.Exceptions4.ThrowRuntimeException(Int32 code, String msg)
   在 Db4objects.Db4o.CS.Internal.ObjectServerImpl.CheckClosed()
   在 Db4objects.Db4o.CS.Internal.ObjectServerImpl.OpenClient() --------------------编程问答-------------------- Db4objects这个玩意儿没讲过啊

补充：.NET技术 ,  ASP.NET