Problem interfacing LHAPDF-6.1.5 with MG5_aMC_v2_4_2

Hello Experts,

I am using Ubuntu 12.04.5 LTS, MG5_aMC_v2_4_2 and LHAPDF-6.1.5.

$ lhapdf-config --prefix
/home/bajarang

I have set the LHAPDFSYS in my ~/.bashrc
export LHAPDFSYS=$HOME
export PATH=${LHAPDFSYS}/bin:${PATH}
export LD_LIBRARY_PATH=${LHAPDFSYS}/lib:${LD_LIBRARY_PATH}

All the pdfs are in :
/home/bajarang/share/LHAPDF/CT10

Also boost version is BOOST_VERSION 104700

I am generating events for p p > W+ process.
with following changes in the run_card.dat
     lhapdf = pdlabel ! PDF set
     10800 = lhaid ! if pdlabel=lhapdf, this is the lhapdf number

I changed the input/mg5_configuration.txt as :
lhapdf = /home/bajarang/bin/lhapdf-config

I get a huge error, some of the last few lines I am pasting below :

/home/bajarang/packages/LHAPDF/LHAPDF-6.1.5/src/yamlcpp/conversion.cpp:57: undefined reference to `std::basic_string<char, std::char_traits<char>, std::allocator<char> >::~basic_string()'
            /home/bajarang/packages/LHAPDF/LHAPDF-6.1.5/src/yamlcpp/conversion.cpp:57: undefined reference to `std::basic_string<char, std::char_traits<char>, std::allocator<char> >::~basic_string()'
            /home/bajarang/packages/LHAPDF/LHAPDF-6.1.5/src/yamlcpp/conversion.cpp:64: undefined reference to `__cxa_guard_abort'
            ../lib//libLHAPDF.a(liblhapdf_yaml_cpp_la-conversion.o): In function `std::basic_string<char, std::char_traits<char>, std::allocator<char> >::_Rep::_M_dispose(std::allocator<char> const&)':
            /usr/include/c++/4.6/bits/basic_string.h:244: undefined reference to `std::basic_string<char, std::char_traits<char>, std::allocator<char> >::_Rep::_M_destroy(std::allocator<char> const&)'
            ../lib//libLHAPDF.a(liblhapdf_yaml_cpp_la-conversion.o): In function `operator==<char, std::char_traits<char>, std::allocator<char> >':
            /usr/include/c++/4.6/bits/basic_string.h:2462: undefined reference to `std::basic_string<char, std::char_traits<char>, std::allocator<char> >::compare(char const*) const'
            /usr/include/c++/4.6/bits/basic_string.h:2462: undefined reference to `std::basic_string<char, std::char_traits<char>, std::allocator<char> >::compare(char const*) const'
            /usr/include/c++/4.6/bits/basic_string.h:2462: undefined reference to `std::basic_string<char, std::char_traits<char>, std::allocator<char> >::compare(char const*) const'
            /usr/include/c++/4.6/bits/basic_string.h:2462: undefined reference to `std::basic_string<char, std::char_traits<char>, std::allocator<char> >::compare(char const*) const'
            collect2: ld returned 1 exit status
            make: *** [../bin/internal/combine_events] Error 1

What am I doing wrong here? Please help. Thanks in advance.