Dear all,
i am using oracle apex 5 with oracle database 12c on windows with firefox.
i dont know whether my approach is right or not, but here my problem is;
i have the following form, based on the Student table. the last three items which are in the Enrollment region are just control items.
when the user click on the update button (the top right button in this case), a process which i created and will explain shortly should update or insert into Student Enrollment Table a row.
the form is below

the last three control items are below;

look at the source which is NULL ( is this okay? i am not sure but this is the only option which worked here)
now, i have created a process as below

the pl/sql code in this process is as below

now when i run the application, it generates the following error;

and the enrollment_date which i select before pressing the update button is as below

before that i tried to create a dynamic action behind the save button, but there were some problems.
what i want to acheive is when the user press the Save button the form should insert or update a row in the student_enrollment table and the form should go back to the report page.
could somebody could guide with the above? generating this case is a bit difficult. i am trying to generate this case on apex.oracle.com but i am facing error which says that this page belongs to different workspace.
Regards.