ClassCastException when try to use DestinationService

Hi, I'm getting a ClassCastException when i use (DestinationService)ctx.lookup(DestinationService.JNDI_KEY); the problem is that lookup returns a null pointer.

I have already tried by adding the reference to application-j2ee-engine.xml file:

<reference reference-type="hard">

<reference-target

provider-name="sap.com"

target-type="service">tc_secdestinations~service

</reference-target>

</reference>

I also have tried to add the tc_sec_destinations_services.jar to my classpath in the explicit and implicit way, but the problem continue.

I hope you can solve my problem.

Thanks