You should not raise message directly like this in that method. Use message_handler to add message.
message_handler ?= CL_PT_REQ_MESSAGE_HANDLER=>IF_PT_REQ_MESSAGE_HANDLER~INSTANCE_GET( ).
CALL METHOD message_handler->add_message
EXPORTING
im_type = msgty
im_cl = msgid
im_number = msgno
im_par1 = msgv1
im_par2 = msgv2
im_par3 = msgdat-msgv3
im_par4 = msgdat-msgv4.
R