[Serusers] build static modules , undefined reference to 'usrloc_exports' ?

hello... I want to build a small and workable ser (let user can sending messages , registering , talking via ser...) , and build needed modules to static modules , what modules should I build in with static modules? I tried built tm,sl,rr,maxfwd,usrloc these modules to static modules , but it has some error...in compiling sr_module.o only when build usrloc modules to static modules, does "usrloc" modules can't build to static modules? or i have missing something?? error msg as follow... sr_module.o (.text+0x5a9):In function 'register_builtin_modules': :undefined reference to 'usrloc_exports' My environment is in RedHat 9.0 Jimmy