If you see 'Logging in', but nothing in the Access Tracker, make sure your controller is configured properly with the ClearPass as RADIUS Server, ClearPass is reachable from the controller, Shared secrets match on Controller and ClearPass.
When the Access Tracker does not show anything, check the Event Viewer in ClearPass. It will probably show in YELLOW that there is a request coming in from an unknown client or with an unmatched shared-secret. If there is nothing in Access Tracker, nor in Event viewer, the request is not getting to ClearPass; do double check controller configuration and network (routing/firewalls/filters) between controller and ClearPass.
If you are in a hurry to make this work, it may be wise to open a case with support (if it is all Dell, use Dell support; if it is Aruba products, use the Aruba TAC).