How to solve the SAXParseException: cvc-elt.1 -> 'bpm-platform'?

Question

I have a bpm-platform.xml, the content of which is :

    <?xml version="1.0" encoding="UTF-8"?>
    <bpm-platform xmlns="http://www.camunda.org/schema/1.0/BpmPlatform"
                  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
                  xsi:schemaLocation="http://www.camunda.org/schema/1.0/BpmPlatform http://www.camunda.org/schema/1.0/BpmPlatform">

      <job-executor>
        <job-acquisition name="default" />
      </job-executor>

      <process-engine name="default">
        <job-acquisition>default</job-acquisition>
        <configuration>org.camunda.bpm.engine.impl.cfg.StandaloneProcessEngineConfiguration</configuration>
        <datasource>java:jdbc/ProcessEngine</datasource>

        <properties>
          <property name="history">full</property>
          <property name="databaseSchemaUpdate">true</property>
          <property name="authorizationEnabled">true</property>
        </properties>

      </process-engine>
    </bpm-platform>

Once this xml is published in my server, I get this error :

SAXParseException: cvc-elt.1: Cannot find the declaration of element 'bpm-platform'.

Can someone please point me in the right direction as to what mistake I am making ?