ME23N printing produce Error in OPEN_FORM for document

Hi all,

when I am trying to send the purchase form to external in ME22N, I've got the following error message in the processing log

Error in OPEN_FORM for document xxxxxxxx.

It produces this error only by this purchase order, all other purchase order can send to external. I try to debug the problem and set the debugger in the form routine

*----------------------------------------------------------------------*
* INCLUDE FM06PE02 *
*----------------------------------------------------------------------*
form entry_neu using ent_retco ent_screen.

data: l_druvo like t166k-druvo,
l_nast like nast,
l_from_memory,
l_doc type meein_purchase_doc_print.

clear ent_retco.
if nast-aende eq space.
l_druvo = '1'.
else.
l_druvo = '2'.
endif.

call function 'ME_READ_PO_FOR_PRINTING'
exporting
ix_nast = nast
ix_screen = ent_screen
importing
ex_retco = ent_retco
ex_nast = l_nast
doc = l_doc
changing
cx_druvo = l_druvo
cx_from_memory = l_from_memory.
check ent_retco eq 0.
call function 'ME_PRINT_PO'
exporting
ix_nast = l_nast
ix_druvo = l_druvo
doc = l_doc
ix_screen = ent_screen
ix_from_memory = l_from_memory
ix_toa_dara = toa_dara
ix_arc_params = arc_params
ix_fonam = tnapr-fonam "HW 214570
importing
ex_retco = ent_retco.
endform.

,but the debugger never pass through the programm and the form routine ENTRY_NEU.

Additional I turn on all option in the debug modes and it does not stop at the point, that I set. Please look at attach files, it gives useful information about my problems.

Thanks so much