Call BAPI_USER_CHANGE from RFC in a visual basic application

Question

Hi all,
we are developing a tool in order to update users info (SU01).
The BAPI involved is BAPI_USER_CHANGE.
We have a table which contains a set of actions. Each action change one field at time. So, if I nedd to change the first name and last name, I call the BAPI two times.
More or less it works but, some time, it seems that a buffer (some where) is not cleared and one user is filled with the data of the previous user in the table of actions.
To specify the USER ID we use:
            Set paramUserName = rfcFunction.Exports("USERNAME")           
            paramUserName.VALUE = USER_ID
To specify one filed value we use the structures (ADDRESS, LOGONDATA, DEFAULTS, ecc):
         Set paramFieldName = rfcFunction.Exports("ADDRESS")
         paramFieldName("FIRSTNAME") = "Wallace"
Of course we set the corresponding X in the fileld name involved of the structure ADDRESSX.
We have used other BAPI (eg. PRGN_RFC_DEL_AGRS_IN_COLL_AGR) which invold tables.
In such case we use the freetable statement to clear the table.
Is the a correspoind statement to clear a structure (like ADDRESS in BAPI_USER_CHANGE) ?
Where I can find a detailed documentation of SAP DLL used to make RFC calls ?
Thanks in advance.
Andrea

Answer 1

Do I need to call BAPI_TRANSACTION_COMMIT for each call of BAPI_USER_CHANGE of only once at the end.
In other words:
Case 1:
while not .eof actions
   BAPI_USER_CHANGE
   BAPI_TRANSACTION_COMMIT
wend
Case 2
while not .eof actions
   BAPI_USER_CHANGE
wend
BAPI_TRANSACTION_COMMIT