User-exit for MIGO, need change GKONT for CO

Question

Good evening,
Dear friends, sorry for my english.
I have made user-exit for MIGO in GGB1 and put on it in SPRO.
I have HKONT=V3100* and corresponding HKONT=1551*( OBYC, group WRX).
Then i run MIGO and make Purchase Order.
In my user exit, if HKONT of first position eq V3100, i must change corresponding HKONT from 1551 to V1551*.
When i make Order, i am run view documents: FI and other HKONTs changed successfully! ( first possition has V3100, second - V1551).
User-exit must work only with sy-tcode = MIGO or MIRO.
But CO documens NOT changed: HKONT(type of cost) eq V3100, but corr GKONT = 1551*...
I also try to use OPEN FI, but have the same picture... (in CO docs V3100* and 1551, but all another docs and FI too - V3100 and V1551*).
I see, that GKONT has only COEP. And this table a cannot see in user-exit.
I think, that FI doc must do CO doc,
but why in
View documents->RW-infodocs->documents CO = it is not change?
Please, answer me? if you can. regards.

Answer 1

Please, view Print-Screen of my problem:
<a href="http://rodendron.blogspot.com/2007/07/user-exit-for-migo.html">http://rodendron.blogspot.com/2007/07/user-exit-for-migo.html</a>
Anybody can help?