[Axapta-Knowledge-Village] what is wrong with my display method

[riz_dynamics]

display LegacyBPNbr LegacyBPNbr()
{

    return inventTable::find(BOM.ItemId).LegacyBPNbr;

}
I am getting the error that table does not contain this field, and I can see 
the item Id field on Bom.
I really appreciate the help