LSMW for Bill of material

Hi everybody, i am doing LSMW for BOM creation using standard batch input program ,i declered the two stuctures and mapped the filelds with respective standard structure fileds , while uploading the flat file data in Assign file step. it is giving error , can any body sugget me in which way i have to give the flat file data for testing the LSMW. Please send the links if u know , that will help for me.

Regards,

rajesh.