cannot add missing drive to array with megacli

I have raid5 nas drive with 20 disk. After having 4 power failure in same hour, nas couldnt be reached. Two of the drives were foreign. I managed to get status to Firmware state: Unconfigured(good)

ouput of MegaCli -LdPdInfo -a0
is as follows;

Virtual Disk: 0
Name:
RAID Level: Primary-5, Secondary-0, RAID Level Qualifier-3
Size:54359418MB
State: Offline
Stripe Size: 64kB
Number Of Drives:20
Span Depth:1
Default Cache Policy: WriteBack ReadAdaptive Cached
Current Cache Policy: WriteBack ReadAdaptive Cached
Access Policy: Read/Write
Disk Cache Policy: Disabled
Number of Spans: 1
Span: 0 - Number of PDs: 20



PD:0 and PD:2 has empty so they are missing drives; which are Unconfigured(good) status.
i am entering
-PdReplaceMissing -PhysDrv \[0:0\] -Array0 -row0 -a0
command to take those disks to the raid but i am not getting any response. As i read from web, it should get an prompt as
Adapter: 0: Missing PD at Array 0, Row 0 is replaced
but i am getting empty line. and i cannot start rebuilding array.

Any idea what i might be missing? Thank you in advance.

you may use the MegaRAID storage Manager from Avago (version 14.11) to connect to the raid and manage it this way.