BAPI_PO_CHANGE and 4.6C

[Sri Neela]

All,
 
Has anyone worked with BAPI_PO_CHANGE and R/3 4.6C and have a minute to
help me??
 
Scenario:
BAPI_PO_CHANGE and R/3 4.6C status is not released for customer in SWO1:
BUS2012
 
I am trying to use this BAPI to change PO line item Tax Code for ME22N,
but apparently not working.  Update is not happening with new tax code
by line item. Have used BAPI_Transaction_Commit to do the commit work
and wait.  Trying to see if anyone else has gone thru. similar
situtation or what steps we have to follow to use unreleased BAPI??
 
Below are some of the OSS notes from SAP, not sure what else I need to
do.. For this BAPI to work for my scenario.
577398    Enjoy PO BAPIs in SAP R/3 Release 4.6B
484692    BAPI_PO_CHANGE Delv. date not considdered
Release 4.6B according to note 197958.
 
Thanks in advance.
 
-Rgds,
Sri Neela