smb40/ smartform help

Hi gurus....

my senior did the purchase order form work by smb40 package both smartform and program.....im on the updation work and corrections,if any...here,i need ur help

the problem now im facing is,in the pur order for the doc type 'ZSTO',the rate(konv-kbetr) is not coming out correctly as per the doc posted in me21n......

how to edit the codes in the smatform....and how to get the amount for this doc type......

pls do the needful with ur examples to me.....on urgent basis

thanks & regards

sankar