Cinder + custom Toshiba drivers saying no valid host

 ERROR cinder.scheduler.flows.create_volume [req-3dc9dea3-3aac-4aac-b4a9-8d6550be5bfb 5071310e57a8491c853490b81ebf5c24 11dd590d1a27428ebb1eb521c701f629] Failed to run task cinder.scheduler.flows.create_volume.ScheduleCreateVolumeTask;volume:create: No valid host was found. No weighed hosts available

error is as above.

Problem statement :

I am writing a driver which contacts the rest api in back end for creating volume.

now There is a file called ToshibaDriver in the Driver and a class which extends ISCSIDriver.

two methods have been over written to check the flow is reaching there,

methods overwriten are

A method __init__
followed by

def check_for_setup_error(self):
pass

def create_volume(self,volume):
print '-------------------------------------------'

Is there any thing or configuration am missing which can fix the problem.

I request some help and thanks
in advance