I have activated ceilometer through the following instruction

First go in devstack directory and search local.conf file local.conf file

Paste the following content

# Enable the ceilometer metering services
 enable_service ceilometer-acompute ceilometer-acentral ceilometer-anotification ceilometer-collector

# Enable the ceilometer alarming services
enable_service ceilometer-alarm-evaluator,ceilometer-alarm-notifier

# Enable the ceilometer api services
enable_service ceilometer-api

`

Run the following command in devstack directory

./unstack.sh ./rejoin-stack.sh

above instruction is given on http://docs.openstack.org/developer/ceilometer/install/development.html (this link)

My dashboard is showing the Resource usage in admin section but it is not showing any graph regarding the resource usage. I already started two instance. But Resource usage panel showing nothing..