Forms :: How To Share PL/SQL Variable Between 2 Forms

I create 2 forms

form 1: I used the Departments table to create this form

in form-level trigger : When-New-Form-Instance

go_block('departments');
execute_query;

there is a control block with name (CTRL)

there is Exit button with trigger When-Button-Pressed exit_form

there is a text item to print the department_id that i select this is for confirmation. I populate this item by (department no) button When-Button-Pressed

my_data.department := :departments.department_id;
:CTRL.TEXT_ITEM8:= :departments.department_id;

Now this part has the global shared pl/sql variable when i press in the button POPULATE_AND_SEND with a trigger When-Button-Pressed

my_data.department := :departments.department_id;
OPEN_FORM('c:Shared_PLSQL_Variablesemployees.fmx',ACTIVATE,NO_SESSION,SHARE_LIBRARY_DATA);

form 2 in this form i used employees table it will display the data that is content in the department selected from the first form it only has form-level trigger When-New-Form-Instance

IF my_data.department IS NOT NULL THEN
SET_BLOCK_PROPERTY('employees',DEFAULT_WHERE,'department_id='||to_char(my_data.department));
:CTRL.TEXT_ITEM8:= my_data.department;
GO_BLOCK('employees');
EXECUTE_QUERY;
END IF;

this is the code in .pll file that i attached in Attached Libraries

PACKAGE my_data IS
department number;
END;

when I run this forms and press in (DEPARTMENT NO) button it's not display any thing in the text item I received this error check the link.

same error when i press in POPULATE AND SEND button to open the other window and execute query.