How to retrieve Tables from custom RFC in SAP

Can anybody tell me plz which method to use in lcconnection to retrieve information from a rfc function where the tables are dynamic build.

the rfc function need 3 parameters - how do i call it with these

function zzfi_hent_ec_opl.

*"----------------------------------------------------------------------

""Local interface:

*" IMPORTING

*" VALUE(UNAME) TYPE SYST-UNAME

*" VALUE(PERNR) TYPE P_PERNR OPTIONAL

*" VALUE(KOST_FROM) TYPE KSTAR OPTIONAL

*" VALUE(KOST_TO) TYPE KSTAR OPTIONAL

*" TABLES

*" O_KOSTELEMLIST STRUCTURE BAPI1030_CELIST

*" O_PROJLIST STRUCTURE ZZFI_S_EC_PROJLIST

im using

selectstatement =|PERNR=00101302,KOST_FROM=“40300”,KOST_TO=“40380”|

with this method

numFound = sapsession.Execute(selectstatement, rstfldlist)

but i dont get the correct results