Problem in creating shared roster group

My eJabberd version is 2.1.6. I want to create shared roster group to block some of the users temporally using mode_filter. In order to create group I installed module mod_admin_extra to my ejabeered server by looking at the blog created at http://vidorsolutions.blogspot.com/2011/01/adding-modules-to-ejabberd-in.... But when I try to execute below command I get below error message.

Command:
ejabberdctl srg_create temp_block MyHost temp_block "'Group to add blocked users'" temp_block

Error:
Problem 'error {badmatch,{aborted,{no_exists,sr_group}}}' occurred executing the command.
Stacktrace: [{mod_admin_extra,srg_create,5},
{ejabberd_ctl,call_command,3},
{ejabberd_ctl,try_call_command,3},
{ejabberd_ctl,process2,3},
{ejabberd_ctl,process,1},
{rpc,'-handle_call_call/6-fun-0-',5}]

Any clue/help to fix this error greatly appreciated.

Thanks...