ldd -r shows missing symbols

Ubuntu Gutsy Gibbon.

The following libvisual-plugins (in the /usr/lib/libvisual-0.4/actor directory) show missing symbols (using ldd -r) and cause some applications to crash and/or the visual simply doesn't work:
actor_flower.so
actor_lv_gltest.so
actor_madspin.so
actor_nastyfft.so

Here is the output of ldd -r actor_flower.so:
undefined symbol: log (./actor_flower.so)
undefined symbol: sqrt (./actor_flower.so)
undefined symbol: visual_timer_elapsed_msecs (./actor_flower.so)
undefined symbol: visual_mem_malloc0 (./actor_flower.so)
undefined symbol: visual_object_get_private (./actor_flower.so)
undefined symbol: visual_plugin_get_random_context (./actor_flower.so)
undefined symbol: visual_timer_has_passed_by_values (./actor_flower.so)
undefined symbol: glColor3f (./actor_flower.so)
undefined symbol: glRotatef (./actor_flower.so)
undefined symbol: glVertex3f (./actor_flower.so)
undefined symbol: visual_timer_start (./actor_flower.so)
undefined symbol: glNormal3fv (./actor_flower.so)
undefined symbol: visual_buffer_set_data_pair (./actor_flower.so)
undefined symbol: visual_mem_free (./actor_flower.so)
        linux-gate.so.1 => (0xffffe000)
        libc.so.6 => /lib/tls/i686/cmov/libc.so.6 (0xb7e2a000)
        /lib/ld-linux.so.2 (0x80000000)
undefined symbol: gluPerspective (./actor_flower.so)
undefined symbol: glDisable (./actor_flower.so)
undefined symbol: glMatrixMode (./actor_flower.so)
undefined symbol: glViewport (./actor_flower.so)
undefined symbol: glBegin (./actor_flower.so)
undefined symbol: glLineWidth (./actor_flower.so)
undefined symbol: glPolygonOffset (./actor_flower.so)
undefined symbol: cos (./actor_flower.so)
undefined symbol: sin (./actor_flower.so)
undefined symbol: visual_object_set_private (./actor_flower.so)
undefined symbol: glLightfv (./actor_flower.so)
undefined symbol: glLoadIdentity (./actor_flower.so)
undefined symbol: glPopMatrix (./actor_flower.so)
undefined symbol: glClearColor (./actor_flower.so)
undefined symbol: visual_video_set_dimension (./actor_flower.so)
undefined symbol: visual_event_queue_poll (./actor_flower.so)
undefined symbol: glEnable (./actor_flower.so)
undefined symbol: glClear (./actor_flower.so)
undefined symbol: visual_audio_get_sample_mixed_simple (./actor_flower.so)
undefined symbol: glMaterialfv (./actor_flower.so)
undefined symbol: visual_random_context_float (./actor_flower.so)
undefined symbol: visual_audio_get_spectrum_for_sample (./actor_flower.so)
undefined symbol: glTranslatef (./actor_flower.so)
undefined symbol: visual_timer_is_active (./actor_flower.so)
undefined symbol: glBlendFunc (./actor_flower.so)
undefined symbol: glEnd (./actor_flower.so)

Is this a missing dependency? Perhaps I have a broken setup? Or perhaps it's a linking/compiling bug?