Try comparing the Model Type of the device working and the one which is notworking ? There is a know issue for one specific device in 10.2 take a look at the below
Symptom: Unable to use NCM as Cisco 819 series devices are modeled as GnCiscoDev and the Device Type is Cisco ASR9000LC.
Resolution: User can perform NCM operations with Cisco 819 series devices modeled as Rtr_Cisco type.
(10.2.0, DE156812, 00345236)