I have a project.it uses a LIB document(p550_01a.lib).I add it to my project. but after linking ,the keil gives out such warning as follow: ***WARNING L1：UNRESOLVED EXTERNAL SYMBOL SYMBOL：SYS_INIT MODULE: MYTEST.OBJ (MYTEST) ***WARNING L2: REFERENCE MADE TO UNRESOLVED EXTERNAL SYMBOL: SYS_INIT MODULE: MYTEST.OBJ (MYTEST) ADDRESS: 07F8H I think my head files and c files is right.Perhaps there is something wrong with my setting of bl51 of keil.please tell me how to resolve such question.I an a beginner of keil.I use keil Uv2.o