Error in bapi API_DELIVERYPROCESSING_EXEC

Hi,

we are trying to create outbound delivery with the help of this bapi , but not able to create it.

we have set documet type = 1 (ie Purchase Order in External System), as sto is from another sap system and idoc is generated while changing sto. So with the help of idoc segment we are trying to create the delivery .Also one warning message 'Conversion factors 0:0 are zero, not defined mathematically' is displaying in return and error message is 'Delivery not possible at the moment'