BIG-IQ issue discovering the standby unit

hello, i am implementing BIG-IQ 6.0.1 and i have a HA pair of big-ip 12.1.x (already configured as active/standby and up and running) i am stuck at the first stage, when i discover/add the ip address of the primary BIG-IP it works properly and the device is added. In addition, i can see on the primary Big-ip GUI that is being managed by big-IQ while i cannot see this message in the GUI of the standby.

 

moreover, on the BIg-IQ, when i access devices -> big-ip cluster -> dsc groups -> then discover i can see the Device group that are configured on the BIg-IP, when i click on i see the below .

 

1- what would be the issue (since i cannot add the standby device 192.168.6.190 because it will throw and error)? 2- how can fix this? 3- shouldn't i see two ip addresses (the primary and standby) when access on the BIG-IQ devices-> BIG-IP devices? note i am using the management interface on the BIG-IQ and BIG-IP for discovery and later on for config/monitoring...

 

Thank and Regards, George