Forms :: Stacked Canvas On Tab Canvas

I've a 2 stacked canvases(canvas_live_appmnt, canvas_cancelled_appmnt) and Tab canvas(cc_main).Now I need to move the stacked canvas on the Tab canvas.I tried writing the When-tab-changed trigger as follows: In the below code I was trying for only one of the stacked canvases.

DECLARE
L_LOCAL_TP_NAME VARCHAR2(30);
BEGIN
L_LOCAL_tp_name := GET_CANVAS_PROPERTY('CC_MAIN',topmost_tab_page);
IF L_LOCAL_tp_name = 'LIVE_APPOINTMENTS' then
SET_VIEW_PROPERTY('CANVAS_LIVE_APPMNT',VISIBLE, PROPERTY_TRUE);
--SET_VIEW_PROPERTY (FIND_VIEW ('CANVAS_LIVE_APPMNT'), DISPLAY_POSITION, 0 , 325);
ELSE
SET_VIEW_PROPERTY('CANVAS_LIVE_APPMNT',VISIBLE, PROPERTY_FALSE);
END IF;
END;