Creating Work Item Using RTC REST API

Hi..

I am new to RTC and am using the REST API of RTC to migrate tickets from another application.

Currently I am using Apache HTTP Components (http://hc.apache.org/) to post the data to RTC. But I am having the following error:
<?xml version="1.0" encoding="UTF-8"?><oslc_cm:error xmlns:oslc_cm="http://open-services.net/xmlns/cm/1.0/">
<oslc_cm:status>400</oslc_cm:status>
<oslc_cm:message>Malformed XML: The prefix "oslc_cm" for element "oslc_cm:factory" is not bound.</oslc_cm:message>
</oslc_cm:error>

I am following the documentation available at https://jazz.net/wiki/bin/view/Main/ResourceOrientedWorkItemAPIv2#Creating_Work_Items.

and my data sample is as follows:
<?xml version="1.0" encoding="UTF-8"?>
<oslc_cm:factory oslc_cm:default="true">
<dc:description>Creating Work Item From REST API</dc:description>
<dc:subject>Creating Work Item From REST API</dc:subject>
<dc:title>Creating Work Item From REST API</dc:title>
</oslc_cm:factory>

Could anyone help or advise.

Many thanks,
Shameem