Problem Setting Rate In Item List

Hi all,

I'm adding a line item to a vendor bill when a person clicks to edit said bill, and I've got most of it working fine.  However, when I try to set the rate for the item to 0, it doesn't work and the rate field is auto populated with value from somewhere.

if ( ! dsvendorship_exists ) {    // add the 'ds vendor ship' line item    nlapiSelectNewLineItem ( 'item' );    nlapiSetCurrentLineItemValue ( 'item', 'item', 19320 );    nlapiSetCurrentLineItemValue ( 'item', 'rate', 0 );    nlapiSetCurrentLineItemText ( 'item', 'location', 'Our Company' );    nlapiCommitLineItem ( 'item' );   }

'ds vendor ship' is a non-inventory item in our system that our accounting department is using to put in the shipping cost of the bill.  The above code adds the line item (if a 'ds vendor ship' line item does not already exist), but the rate always comes out to 22.00 (I have no idea where it is getting that value from).  I've tried adding the rate as 0, 0.00, '0', and '0.00' to no avail.  Any help will be greatly appreciated.