[SYS21] Item costing

Standard System v3.5.2b SP4

We use manufacturing to enter/maintain item costs (11/MDC)
We then transfer the costs to inventory (4/MDC)

I have an item that should have zero costs,
this item was maintained (in error) and had costs put
into it. This has 'blown out' our stock valuation.

I have maintained the item cost (using 4/MDC) putting
it back to zero, but when I transfer (using 4/MDC) it
goes on an error report 'Zero Man Standard' and does
not update the inventory costs.

Question : How can I force this item through the
          update with zero cost??

Thanks,
Gary.