fix append not defined bug.
fix append not defined bug.

JPO1/vincent,springcoil/vincent,CrazyGuo/vincent,chiu/vincent,JPO1/vincent,taohaoge/vincent,myusuf3/vincent,wrobstory/vincent,chiu/vincent,KAPPS-/vincent,qiwsir/vincent,myusuf3/vincent,xunyou/vincent,taohaoge/vincent,CrazyGuo/vincent,KAPPS-/vincent,xunyou/vincent,springcoil/vincent,qiwsir/vincent,wrobstory/vincent