Oracle Forms

Hi,
I am having a wierd problem:
Scenario:
I have a datablock of 40 columns.
I put 1 (say col-1 on page_1 and col-21 on page_2) column each on two different TAB pages.
I created 2 stacked canvases: page_1_stacked & page_2_stacked
I put col-2 to col-10 on page_1_stacked
and col-22 to col-40 on page_2_stacked

I used the following code to show/hide the appropriate cols/stack canvases when the users changes Tab pages:
[when-tab-page-changed
if (:system.tab_new_page ='PAGE_1')
then
show_view('PAGE_1_STACKED');
hide_view(''PAGE_2_STACKED'');

elsif (:system.tab_new_page ='PAGE_2')
then
hide_view('PAGE_1_STACKED');
show_view(''PAGE_2_STACKED'');
end if;

Problem:
Everything seems to work fine, the stacked canvases show/hide as expected, but --->as soon as I put my cursor in any column on TABBED PAGE (here col-1 or col-21), all the stacked canvases vanish
-->if as a result of above case where I put the cursor in a tabbed-page col and canvas vanished, I navigate to the next field (which is on canvas), the canvas shows up (which is normal)....but then this canvas wont get hidden with my hide view... and end up with all stacked canvases shown together or none at all

I have played around with all the properties and am really trapped.

Please help!

Thanks.