Sage 300

Am gettingthe below errors What might cause this to happen? Wjhat can i do to fix this? Purchase Order Line: PO0311816, 10, 700511-IRGP E: Item number does not exist. E: Unit of measure EA does not exist. Purchase Order Line: PO0311816, 14, 9533266…

Dear, I am facing a problem in sage 300, I already have two companies in sage 300, but when I open a new company one old one company disconnected from data base, now my old company doesn't show any thing, kindly advise me