boost::asio::serial_port: No data received/transmitted on linux

Hi, I am using the boost::asio::serial_port on windows without probplems. Now I have still one maschine running on windows and one on linux. Using a serial port connection via putty works to send and transmit data between the two maschines. Now I start a serial_port on the linux system and nothing works but also no errors are thrown. Basically I do a...

socket.open("/dev/ttyAMA1", ec);
socket.set_option(serial_port_base::baudrate(9600), ec);
socket.set_option(serial_port_base::character_size(8), ec);
socket.set_option(serial_port_base::parity(serial_port_base::parity::none), ec);
socket.set_option(serial_port_base::stop_bits(serial_port_base::stop_bits::one), ec);
socket.set_option(serial_port_base::flow_control(serial_port_base::flow_control::none), ec);

The error code variable ec never indicates an error.
If I use e.g. an not existing device, I get an error as expected.

For receiving/transmitting I use...

socket.async_read_some(mutable_buffer(...), std::bind(...));
async_write(socket, const_buffer(...), std::bind(...));

...functions. Am I missing something?