about hook system lib

hi, I just want hook a method in libdvm.so, the method name is "dvmResolveClass", first issue is " si = (struct soinfo )dlopen( soname, 4 / RTLD_NOLOAD */ );" there is no flag RTLD_NOLOAD. than I change it to RTLD_GLOBAL. in this way, I can find the symbol, and get "sym_offset=14", but at last, I get a message "Unable to find symbol in the reloc tables". what wrong?
