Sales Order gets created inspite of Item not exisitng

We are sending Saes Order Details from SQL Database to SAP R/3 thro XI3SR1.

In the Database_To_SAP map, we are performaing a lookkup for Material / ITem availabilty in R/3 (thro RFC Func module). IF the material does not exist in R/3, the look up function Module will return an error message. We are not able to catch this message and terminate the process (BPM of course). The Sales Order is stillg etting created without Material Number in it.

Please advise where do we need to catch this error and terminate the process in BPM. We also need to generate an e-mail to this effect.

Thanks,

Bhaskar Ghandikota