frm-41052 cannot find window:invalid id

Hello,

We upgraded from 10g to 11g. 

We have a calendar object that is not working.

The calendar is a .pll file that dynamically adds ui components to a window.

Inside the calendar.pll it fails on on the following line.

date_window := find_window('date_lov_window');

The form that iuses the component has a window called 'DATE_LOV_WINDOW'

The form also has a canvas called 'DATE_LOV_CANVAS' that is assigned to window 'DATE_LOV_WINDOW'

Is this how everything is suppose to connect or am I missing something?

I have recompiled the .pll and the forms .