CKAN Resource URL empty

Question

I'm integrating Orion and Cygnus_Ngsi with CKAN. I have configured in Cygnus the CKAN sink as following:

cygnus-ngsi.sinks.ckan-sink.channel = ckan-channel
cygnus-ngsi.sinks.ckan-sink.type = com.telefonica.iot.cygnus.sinks.NGSICKANSink
cygnus-ngsi.sinks.ckan-sink.api_key = ba753aae-7c1f-XXXX-XXXXX-cf893100ab53
cygnus-ngsi.sinks.ckan-sink.ckan_host = ckan host
cygnus-ngsi.sinks.ckan-sink.ckan_port = 8080
cygnus-ngsi.sinks.ckan-sink.orion_url = http://orion ip:1026
cygnus-ngsi.sinks.ckan-sink.attr_persistence = row
cygnus-ngsi.sinks.ckan-sink.batch_size = 100
cygnus-ngsi.sinks.ckan-sink.batch_timeout = 30

After creating a subscription in Orion, performing an update context, the context data are stored in CKAN but the CKAN resource URL is not valued, it is NULL. Which changes I should make in order to have the resource Url valued and download the resource in CKAN? Thanks