linker error with boost regex and g++

I have the following makefile:
CC := g++

MACHINE_OPTS := -mtune=athlon64

INCLUDE_PATH := /home/jaydutt/boost_1_33_1
LIB_PATH := /home/jaydutt/boost_1_33_1/bin/boost/libs/regex/build/libboost_regex.a/gcc/debug

CC_OPTS := $(MACHINE_OPTS) -Wall -Werror

expr: main.o expr.o
      $(CC) $(CC_OPTS) -L$(LIB_PATH) main.o expr.o

main.o: main.cpp expr.h
      $(CC) $(CC_OPTS) -I$(INCLUDE_PATH) -c main.cpp

expr.o: expr.cpp expr.h
      $(CC) $(CC_OPTS) -I$(INCLUDE_PATH) -c expr.cpp

pre: expr.cpp expr.h
      $(CC) $(CC_OPTS) -I$(INCLUDE_PATH) -E expr.cpp

clean:
      rm -f *~ *.o a.out

Boost libraries are built and stored in ~/boost_1_33_1/...

when I try to make expr target, I run into linker error:
expr.o: In function `boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::assign(char const*, char const*, unsigned int)':
expr.cpp:(.text._ZN5boost11basic_regexIcNS_12regex_traitsIcNS_16cpp_regex_traitsIcEEEEE6assignEPKcS7_j[boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::assign(char const*, char const*, unsigned int)]+0x27): undefined reference to `boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::do_assign(char const*, char const*, unsigned int)'

I am sure something is wrong with linker options. or the libraries. I tried to find which obj file defined the desired function and it is .../libboost_regex.a/gcc/debug/instances.o. I added the fully qualified path to makefile only to end up with more undefined references.Start Free Trial