define scrap qty. in BOM if scrap is over then finished item

hi everybody

i am useing NAV2009R2. my prob. is this- we made a production BOM of Item A

Finished Item = Item A
qty. of Finished Item = 200 gms.
qty. of scrap Item = 400 gms.
Total qty. of Raw = 600 gms.
Scrap % = 200%
now prob. is this in BOM of Item A scrap % is greater then 100% of Finished Item so we have not define it. so pls. help me. how i manage it.

Thanks in advance

Regards