Manish,
Now that you have used the right method, problem is with the format of the body.
A sample request body looks as below. (http://www.odata.org/documentation/odata-v2-documentation/operations/#26_Updating_Entries)
<?xml version="1.0" encoding="utf-8" standalone="yes"?>
<Entry xml:base="http://services.odata.org/OData/OData.svc/"
xmlns:d=" http://schemas.microsoft.com/ado/2007/08/dataservices"
xmlns:m=" http://schemas.microsoft.com/ado/2007/08/dataservices/metadata"
xmlns="http://www.w3.org/2005/Atom">
<id>http://services.odata.org/OData/OData.svc/Products(1)</id>
<title type="text"></title>
<updated>2010-02-28T10:23:02Z</updated>
<author>
<name />
</author>
<Link rel="edit" title="Product" href="Products(1)" />
<category term="DataServiceProviderDemo.Product"
scheme="http://schemas.microsoft.com/ado/2007/08/dataservices/scheme" />
<content type="application/xml">
<m:properties>
<d:ID m:type="Edm.Int32">1</d:ID>
<d:Name>Milk</d:Name>
<d:Description>Low fat milk</d:Description>
<d:ReleaseDate m:type="Edm.DateTime">1995-10-21T00:00:00</d:ReleaseDate>
<d:DiscontinuedDate m:type="Edm.DateTime" m:null="true" />
<d:Rating m:type="Edm.Int32">4</d:Rating>
<d:Price m:type="Edm.Decimal">4.5</d:Price>
</m:properties>
</content>
</Entry>
That is it has an <?xml> and <Entry> tags.
You do not seem to be passing <Entry> tag.
Thanks
Krishna
