Item Inventory Add or Modify: 0x80040400: QuickBooks found an error when parsing the provided XML text stream

I am getting the above error Because of  <PurchaseCost> tag. But don't know what I am doing wrong here. If I omit <PurchaseCost> it works. I don't have XML Validator and VERBOSE log doesn't show anything.

<?xml version="1.0" encoding="utf-8"?>
<?qbxml version="13"?>
<QBXML>
<QBXMLMsgsRq onError="stopOnError">
<ItemInventoryAddRq requestID="567897">
<ItemInventoryAdd>
<Name>585928</Name>
<ParentRef><ListID>800004E2-1655395899</ListID></ParentRef>
<SalesDesc >CTC 100</SalesDesc>
<SalesPrice>100</SalesPrice>
<IncomeAccountRef>
<FullName>Sales</FullName>
</IncomeAccountRef>
<COGSAccountRef>
<FullName>Cost of Goods Sold</FullName>
</COGSAccountRef>
<PrefVendorRef>
<ListID >80002369-1532618859</ListID>
</PrefVendorRef>

<PurchaseCost >100</PurchaseCost>

<PurchaseDesc >CTC 100</PurchaseDesc>
<ExpenseAccountRef>
<FullName>Cost of Goods Sold</FullName>
</ExpenseAccountRef>
<AssetAccountRef>
<FullName>Inventory Asset</FullName>
</AssetAccountRef>
</ItemInventoryAdd>
</ItemInventoryAddRq>
<DataExtModRq>
<DataExtMod>
<OwnerID>0</OwnerID>
<DataExtName>SKU</DataExtName>
<ListDataExtType>Item</ListDataExtType>
<ListObjRef>
<FullName>585928</FullName>
</ListObjRef>
<DataExtValue>585233</DataExtValue>
</DataExtMod>
</DataExtModRq>
</QBXMLMsgsRq>
</QBXML>