I had the same issue - I have created a new service in Icinga, but no Graph was displayed for it.
When I added “&graph_debug=1” to Icinga url, I have seen log message that 0 metrics was fetched.
I have opened the Graphite UI at http://localhost:4322/ and found graphs for other services, but the new one was not here too.
Then have I found hint here: retention in /etc/carbon/storage-schemas.conf should be aligned with the check_interval of the service, otherwise Graphite does not aggregate metrics correctly sometime - I have changed the check_interval to “1m” as the retention period in carbon and it works now 