diff --git a/servlet/rpc-servlet.go b/servlet/rpc-servlet.go
index 8957f20..733c18c 100644
--- a/servlet/rpc-servlet.go
+++ b/servlet/rpc-servlet.go
@@ -60,9 +60,9 @@ func (s *RPCServlets) Handle(servletCtx server.ServletCtx,
 
 	if nil != _clientType && nil != _sessionID && nil != _targetID {
 		md = metadata.Pairs(
-			og.GRPCClientTypeKey, _clientType.(og.ClientType).String(),
-			og.GRPCSessionIDKey, _sessionID.(string),
-			og.GRPCTargetIDKey, _targetID.(string),
+			og.GRPCClientTypeKey.String(), _clientType.(og.ClientType).String(),
+			og.GRPCSessionIDKey.String(), _sessionID.(string),
+			og.GRPCTargetIDKey.String(), _targetID.(string),
 		)
 	}
 
@@ -77,15 +77,15 @@ func (s *RPCServlets) Handle(servletCtx server.ServletCtx,
 			// grpc exec method call
 			src, err = sc.NewRequest(msg)
 			if nil != err {
-				logging.Logger().Errore(err)
+				logging.Logger().Error(err)
 				break
 			}
 
 			method = src.Method()
 			params, err = src.Params()
 			if nil != err {
-				logging.Logger().Errore(err)
-				s.writeError(crp.E_BAD_PARAMS, "", err)
+				logging.Logger().Error(err)
+				s.writeError(src, writeChan, crp.E_BAD_PARAMS, "", err)
 				break
 			}
 
@@ -93,8 +93,8 @@ func (s *RPCServlets) Handle(servletCtx server.ServletCtx,
 			grpcReply, err = ogeg.Exec(grpcCtx, method, params...)
 			replyBuff, err = src.NewResponseWithString(grpcReply, err)
 			if nil != err {
-				logging.Logger().Errore(err)
-				s.writeError(crp.E_INTERNAL, "", err)
+				logging.Logger().Error(err)
+				s.writeError(src, writeChan, crp.E_INTERNAL, "", err)
 				break
 			}
 
@@ -107,7 +107,7 @@ func (s *RPCServlets) Handle(servletCtx server.ServletCtx,
 
 }
 
-func (s *RPCServlets) writeError(src crp.ServerRequestCodec, writeChan chan<- []byte, code int, message string, data interface{}) {
+func (s *RPCServlets) writeError(src crp.ServerRequestCodec, writeChan chan<- []byte, code crp.ErrorCode, message string, data interface{}) {
 	if !src.HasResponse() {
 		return
 	}
@@ -120,7 +120,7 @@ func (s *RPCServlets) writeError(src crp.ServerRequestCodec, writeChan chan<- []
 
 	buf, err := src.NewResponse(nil, pErr)
 	if nil != err {
-		logging.Logger().Errore(err)
+		logging.Logger().Error(err)
 		return
 	}
 	writeChan <- buf