OpenMP link error on Mac OS X 10.6

[Gib Bogle]

Hi,

I can build my DLL using gfortran on Windows 7, and on Linux, but I'm 
encountering a problem on Mac OS X (with gfortran version 4.5.1).  The compiling 
is without errors, but the link stage gives this error:

Undefined symbols:
"_omp_set_num_threads_", referenced from ...
"_omp_get_thread_num_", referenced from ...

I'm using the flags "-fopenmp -lgomp".  Since there are no error messages during 
the compiling, and the OpenMP library is where it should be, and it worked on 
Linux, I'm puzzled. Can someone throw any light on this?

Thanks
Gib