XML : Can not transform data using Xml to Jaxb Transformer : Mule Esb

I tried to transform my soap web service data.I used xml to Jaxb transformer... But I got following error

Root Exception stack trace: org.mule.api.transformer.TransformerException: An invalid return type "class [B" was specified for transformer "JAXBMarshallerTransformer" at org.mule.module.xml.transformer.jaxb.JAXBMarshallerTransformer.doTransform(JAXBMarshallerTransformer.java:119) at org.mule.transformer.AbstractTransformer.transform(AbstractTransformer.java:419) at org.mule.DefaultMuleMessage.getPayload(DefaultMuleMessage.java:377) + 3 more (set debug level logging or '-Dmule.verbose.exceptions=true' for everything)

My flow is as follow

   <flow name="test123Flow">          <http:listener config-ref="HTTP_Listener_Configuration" path="/student" doc:name="HTTP"/>          <ws:consumer config-ref="Web_Service_Consumer" operation="getAllStudentData" doc:name="Web Service Consumer"/>          <mulexml:jaxb-xml-to-object-transformer returnClass="org.test.StudentDemo" jaxbContext-ref="JAXB_Context" doc:name="XML to JAXB Object"/>          <logger message="#[payload]" level="INFO" doc:name="Logger"/>      </flow>    

How can I solve this error?