[sr-dev] cannot load websocket module

i built latest master and got error when trying to load websocket module: 0(10759) ERROR: <core> [sr_module.c:588]: ERROR: load_module: could not open module </usr/lib/sip-proxy/modules/websocket.so>: /usr/lib/sip-proxy/modules/websocket.so: undefined symbol: ws_keepalive_mechanism is there a bug in websocket module or am i missing something? i read websocket readme and didn't find anything missing. i have not defined keepalive_mechanism variable in config. -- juha