Controller Troubles for setting brightness programmatically

[Urs Hofer]

Hi All

I'm in troubles with Controllers in Gstreamer 1.2.

The following code compiles flawlessly, but does not do anything but throwing an GStreamer-CRITICAL Message
gst_object_add_control_binding: assertion 'binding->pspec' failed.

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/* volume fades */
GstControlSource  * cs1 = gst_interpolation_control_source_new ();
GstControlBinding * binding = gst_direct_control_binding_new (GST_OBJECT_CAST (pipeline), "brightness", cs1);
gst_object_add_control_binding (GST_OBJECT_CAST (pipeline), binding);

/* set interpolation mode */
g_object_set (G_OBJECT(cs1), "mode", GST_INTERPOLATION_MODE_LINEAR, NULL);

/* set control values */
GstTimedValueControlSource * tvcs = (GstTimedValueControlSource *) cs1;
gst_timed_value_control_source_set (tvcs, 0 * GST_SECOND, 0);
gst_timed_value_control_source_set (tvcs, 1 * GST_SECOND, 1);
gst_object_unref (cs1);	

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Same happens if I want to change "volume". It happens also if I am referring to the 
sink element or the playbin pipeline.

Has anyone a hint? 
Best,
Urs Hofer