Problem with form IDao Inherited a New DAO Interface

[汪彬彬]

Hi,
  i have two interface:IBaseDao, IFlowDao. IFlowDao inherited from IBaseDao.
  IBaseDao have a method, named QueryForObjectByID(string id). class 
BaseMapperDao implement interface IBaseDao and interface IDao。FlowMapDao 
inherited from BaseMapperDao and implement IFlowDao。The class
diagram is:

        IBaseDao<|-- IFlowDao
        IBaseDao,IDao <|-- BaseMapperDao
        BaseMapperDao,IFlowDao <|--     FlowMapDao。

But，i have a Exception:
        Method 'QueryForObjectByID' in type 
'ProxyInterfaceMapperDAOBaseMapperDao_IBaseDao_IDao_ISerializable' from 
assembly 'DynamicAssemblyProxyGen, Version=0.0.0.0, Culture=neutral, 
PublicKeyToken=f362209d9bee91d8' does not have an implementation. 

I have write QueryForObjectById in class BaseMapperDao.
I don't know how to resolve the exception.Please Help me ,thanks.