error while loading shared libraries

I have a project organized as

\bin\cmain
\lib\libxmlrpc_client++.a
\lib\libxmlrpc_client++.so.4
\lib\libxmlrpc_client++.so.4.16

My c program cmain need to dynamically link clib.so.4. While I compile the code, I use -L.../lib to indicate directory lib and use -lxmlrpc_client++. However, my code get error while loading shared libraries:

libxmlrpc_client++.so.4: cannot open shared object file: No such file or directory

Any ideas to fix this?

PS: Problem solved, a good reference to the problem: http://gcc.gnu.org/ml/gcc-help/2005-12/msg00017.html