Sorry to rehash an old thread, I must be only person that just can not get this to work.... here is my build output: /usr/bin/make -f nbproject/Makefile-Debug.mk SUBPROJECTS= .build-conf make[1]: Entering directory `/home/etienne/NetBeansProjects/mingle' mkdir -p build/Debug/GNU-Linux-x86 g++ -c -g -o build/Debug/GNU-Linux-x86/main.o main.cc mkdir -p build/Debug/GNU-Linux-x86 g++ -c -g -o build/Debug/GNU-Linux-x86/server.o server.cc mkdir -p build/Debug/GNU-Linux-x86 g++ -c -g -o build/Debug/GNU-Linux-x86/client.o client.cc mkdir -p dist/Debug/GNU-Linux-x86 g++ -o dist/Debug/GNU-Linux-x86/mingle build/Debug/GNU-Linux-x86/main.o build/Debug/GNU-Linux-x86/server.o build/Debug/GNU-Linux-x86/client.o -lpthread build/Debug/GNU-Linux-x86/server.o: In function `mingle::server::accept()': /home/etienne/NetBeansProjects/mingle/server.cc:36: undefined reference to `mingle::server::handle_accept(mingle::client*, asio::error_code const&)' collect2: ld returned 1 exit status make[1]: *** [dist/Debug/GNU-Linux-x86/mingle] Error 1 make[1]: Leaving directory `/home/etienne/NetBeansProjects/mingle' make: *** [.build-impl] Error 2 Build failed. Exit value 2. Here is the code that complains: void server::accept( ){ client* connection = new client( acceptor_.io_service()); client_.push_back(connection); acceptor_.async_accept(connection->socket(), boost::bind(&mingle::server::handle_accept, this,connection,asio::placeholders::error)); };//accept void handle_accept( client* connection, const asio::error_code& ec ) { };//handle_accept The header file: namespace mingle { class server { public: server( asio::io_service&, short ); ~server() throw(); private: void accept(); void handle_accept( client*, const asio::error_code& ); std::vector<client*> client_; asio::ip::tcp::acceptor acceptor_; protected: }; }; Now why would the linker of all things complain that it just can not find the handle_accept method? I modeled it after the online examples with one adjustment - the client is not a Meyer's singleton like class. Packaged information: Package: libasio-dev Priority: optional Section: universe/devel Installed-Size: 1404 Maintainer: Ubuntu MOTU Developers <ubuntu-motu@lists.ubuntu.com> Original-Maintainer: Simon Richter <sjr@debian.org> Architecture: all Source: asio Version: 0.3.8~rc3-2 Depends: libboost-dev Recommends: libssl-dev Filename: pool/universe/a/asio/libasio-dev_0.3.8~rc3-2_all.deb Size: 149402 MD5sum: fe9a5519552f5d2703238e18c85a5acb SHA1: 09fc70379b840dbba1654544b9299d11c39a6edb SHA256: 38d69bbb72ea825c8be711e407b56bc871d97d6b29693ede3a6ac05f55edc925 Description: cross-platform C++ library for network programming asio is a cross-platform C++ library for network programming that provides developers with a consistent asynchronous I/O model using a modern C++ approach. It has recently been accepted into Boost. . This package contains the development header files. Bugs: mailto:ubuntu-users@lists.ubuntu.com Origin: Ubuntu Thank you, Etienne Pretorius