window_name isn't part of form form_name.
You've referenced a window that isn't attached to
a form. Window_name is the name of the window that isn't attached
to the form form_name.
Common solutions are:
- Reference the correct form when you
reference a window.
- Save each form before referencing windows
in it. Be sure to save the form and any windows associated with the
form before attaching scripts to, or referencing windows or window
fields, for the form.