Invalid USERENV parameter

I am in the process of moving all custom events from Apps8 to Apps10. I am able  to get all custom events functioning after some modification except for events which call "Error_SYS.Record_General()"

When the event is triggered it displays this: https://i.ibb.co/m4Wf1vF/Error.png

For instance the message above is displayed when a user changes the count in the "Count Per Inventory Part" screen but does not add a note : a note needs to be added as to why the count is being changed or else the record will not save.

The Event Action is below:

DECLARE

BEGIN



IF( '&NEW:NOTE_TEXT' IS NULL) THEN

Error_SYS.Record_General('Error','Please add a note in the "Notes" field '); 

END IF;

END;

The body and declaration of Error_SYS.Record_General is the same in Apps8 as it is in Apps10 so my code is correct.

Any help with this error would be appreciate