Multiple purchase order imports

Hi, Although working fine previously, all of a sudden when I do a bulk import of purchase orders it is only recognising the first purchase order number and importing all the others into that one supplier.  If I import the purchase orders separately they are fine of course but for a bulk import I am having the above issue.  Any advice?  I have checked the import file and all the PO numbers are showing on the CSV file before importing, so it's like MYOB is not recognising them all. Accountright. Thanks, Trish