I tried POST for same uri , it works for me. Can you check with this payload?
payload:
<?xml version="1.0" encoding="UTF-8"?>
<entry xmlns="http://www.w3.org/2005/Atom" xmlns:d="http://schemas.microsoft.com/ado/2007/08/dataservices" xmlns:m="http://schemas.microsoft.com/ado/2007/08/dataservices/metadata">
<content type="application/xml">
<m:properties>
<d:ProductName>Play1 Movie1</d:ProductName>
<d:ChangedAt>2016-03-08T11:37:04.8240000</d:ChangedAt>
<d:TaxTariffText>Regular VAT</d:TaxTariffText>
<d:ProductID>AB-1002</d:ProductID>
<d:DimensionUnit>CMT</d:DimensionUnit>
<d:WeightUnitText>Kilogram</d:WeightUnitText>
<d:UnitPrice>13000.00</d:UnitPrice>
<d:ProductKey>005056A216B81EE5B9A4428455AE6C2F</d:ProductKey>
<d:WeightMeasure>2400.000</d:WeightMeasure>
<d:ProductWidth>37000.000</d:ProductWidth>
<d:DimensionUnitText>Centimeter</d:DimensionUnitText>
<d:SupplierID>0100000040</d:SupplierID>
<d:ProductDescription>
CD-RW, DVD+R/RW, DVD-R/RW, MPEG 2 (Video-DVD), MPEG 4, VCD, SVCD, DivX, Xvid
</d:ProductDescription>
<d:ProductCategory>Portable Players</d:ProductCategory>
<d:TaxTariffCode>1</d:TaxTariffCode>
<d:QuantityUnit>EA</d:QuantityUnit>
<d:ProductTypeCode>PR</d:ProductTypeCode>
<d:QuantityUnitText>Each</d:QuantityUnitText>
<d:WeightUnitCode>KGM</d:WeightUnitCode>
<d:SupplierName>Chemia A Technicznie Fabryka</d:SupplierName>
<d:CurrencyCode>PLN</d:CurrencyCode>
<d:ProductHeight>6000.000</d:ProductHeight>
<d:CurrencyText>Polish Zloty (new)</d:CurrencyText>
<d:ProductDepth>24000.000</d:ProductDepth>
<d:SupplierGuid>005056A216B81EE5B996868F88330C2F</d:SupplierGuid>
</m:properties>
</content>
</entry>
Regards,
JK