here is discovery status of discovered divices:

    AGENT NAME                             V      ADDRESS                              SNMP  ICMP  

EX4200-00                      V2C 10.255.32.138                           TRUE  OK     

QDS3213-B6910            V2C 10.5.80.15                              TRUE  UNKNOWN

MXK819                        V2C 10.222.29.82                            TRUE  OK     

S3300-SEC-A                  V2C 10.5.33.33                              FALSE OK     

EX4200-01                      V2C 10.255.160.84                           TRUE  OK     

B6910                      V2C 10.5.31.151                             TRUE  UNKNOWN

B6910                    V2C 10.5.32.164                             TRUE  UNKNOWN

B6910                      V2C 10.5.32.149                             TRUE  UNKNOWN

If you haven't already, please enable Discovery Debug and rediscover one of the devices in question.

Discovery debug commands- http://support.emc.com/kb/496761

Dear Bruce,

Thanks, you mentioned right clue and after enabling discover with debug and discovering again with the help of mentioned article we found that there was issue with certification of devices which is now under process of resolution from customer.

again thank you.