‎I am getting following errror message while creating devices from dmx

I am getting following errror message while creating devices from dmx

symconfigure -sid **** -cmd "create dev count =2,size=18590 cyl,emulation=FBA,config=RAID-5,data_member_count=7;" -v preview

Execute a symconfigure operation for symmetrix '00019010****' (y/ ) ? y

A Configuration Change operation is in progress. Please wait...

Establishing a configuration change session...............Established.

Processing symmetrix 00019010****

{

create dev count=2, size=18590 cyl, emulation=FBA, config=RAID-5,

data_member_count=7 , mvs_ssid=0;

}

Performing Access checks..................................Allowed.

Checking Device Reservations..............................Allowed.

Submitting configuration changes..........................Failed.

Definition 1 is in error:

Could not find disks that satisfy our mirror/RAID policy

Terminating the configuration change session..............Done.

The configuration change session has failed.

Please help me to rectify the error .i got the error even though i specified the diskgroup.

symconfigure -sid **** -cmd "create dev count =2,size=18590 cyl,emulation=FBA,config=RAID-5,data_member_count=7,disk_group=1;" -v preview