CRM API, Adding Sales orders

Hello,

I was trying to use the insetRecords method to add Sales Orders to the CRM.

All the fields like Account Name, and contact name are valid.

But I get an error whenever I query the API, The error is " 4401 Unable to populate data, please check if mandatory value is entered correctly".

This is the XML I sent,

<SalesOrders>
<row no='1'>
    <fieldlabel value='Subject'>Test Subject</fieldlabel>
    <fieldlabel value='Contact Name'>Mr. Kaustabh Prasad</fieldlabel>
    <fieldlabel value='Due Date'>03/03/2010</fieldlabel>
    <fieldlabel value='Carrier'>Aramex</fieldlabel>
    <fieldlabel value='Status'>In Production</fieldlabel>
    <fieldlabel value='Account Name'>Sudyog Infratech</fieldlabel>
    <fieldlabel value='Product Name'>6 inch by 4 inch Stickers</fieldlabel>
    <fieldlabel value='Quantity'>2000</fieldlabel>
    <fieldlabel value='Unit Price'>0</fieldlabel>
    <fieldlabel value='List Price'>2</fieldlabel>
</row>
</SalesOrders>

Please let me what is causing the error, and what is the mistake I am doing.

Thanks,