How to get media uri from GstPlayBin/RygelPlaybinRenderer?

I am trying to write a DLNA renderer(using librygel-renderer-gst) for my own project and I am in some troubles.

My effort is as follows:

code1:

g_object_get(G_OBJECT(data.playbin), "current-uri", uri);

error1:

g_object_get_valist: object class 'GstPlayBin' has no property named '\x90w@\u0002'

code2:

cout << rygel_media_player_get_uri((RygelMediaPlayer*)data.renderer);

error2:

/usr/bin/ld: CMakeFiles/opengl_ex.dir/main.cpp.o: undefined reference to symbol 'rygel_media_player_get_uri'

/usr/lib/librygel-renderer-2.6.so.2: error adding symbols: DSO missing from command line

I just can not figure out what made the errors, are there any other means to get the uri from GstPlayBin or RygelPlaybinRenderer?

regards

Liangzu