diff -r cbb1bfb7ebfb -r edd273b3192a qtms/src/qtmsvolumeeffectimpl.cpp
--- a/qtms/src/qtmsvolumeeffectimpl.cpp	Fri May 14 16:21:14 2010 +0300
+++ b/qtms/src/qtmsvolumeeffectimpl.cpp	Thu May 27 13:19:19 2010 +0300
@@ -57,14 +57,14 @@
     }
 
 gint QTMSVolumeEffectImpl::AddObserver(TMS::TMSEffectObserver& obsrvr,
-        gpointer /*user_data*/)
+        gpointer user_data)
     {
     gint ret(QTMS_RESULT_SUCCESS);
 
     if (iEffect)
         {
         ret = static_cast<TMSVolumeEffect*> (iEffect)->AddObserver(obsrvr,
-                NULL);
+                user_data);
         }
     return ret;
     }