Bill Variance Journal

I understand that we need to set up a bill variance account for differences between item receipt and invoice price to clear the 'Invoiced Received Not billed' account.  I have set up the variance expense account and I have changed the accounting preferences, the item/transaction tab and put the variance account number in the ‘Default Bill Price Variance Account’ line but when I have tested to see if this has worked by attempting to 'Post Vendor Bill Variances' I keep getting a message that says 'Bill Variance Account is Missing'.
I've tried the mass update tool to ensure this account is attached to all the items but its already attached, any ideas what the problem could be?