wcf 序列化参数 出错

[vimson999]

There was an error while trying to serialize parameter http://tempuri.org/:obj. The InnerException message was 'Type 'Tim.WCFService.Contract.DataContract.hia' with data contract name 'hia:http://schemas.datacontract.org/2004/07/Tm.WCFService.Contract.DataContract' is not expected. Add any types not known
statically to the list of known types - for example, by using the KnownTypeAttribute attribute or by adding them to the list of known types passed to DataContractSerializer.'. Please see InnerException for more details.

错误如上

大家有没有遇到过类似的问题，多谢了。