Hi,
don't pass the subject in create_document method of cl_bcs
use the method set_message_subject.
data: subject type string value 'this is my subject.....up to 120 character'.
call method send_request->set_message_subject
exporting
ip_subject = sub .
this will set the subject of more than 50 chars, subject of string type has limitation that it can only pass 255 character.
thank you!!