F5 GTM sync issues

I'm trying add a new GTM into the a existing GTM sync group which already has 2 GTMs in it. The existing GTM sync group GTMs are on version 11.4.1 and new GTM(bloor-f5g1) is on version 11.6.0. From what I read on the F5 docs, the software versions doesn't have to be same on all the GTMs. However I'm getting the following error everytime when I try to add the new GTM.

    [root@bloor-f5g1:Active:Standalone] config  gtm_add 100.100.100.10
    WARNING: Running this script will wipe out the current configuration
    files (bigip_gtm.conf, named.conf and named zone files) on the BIG-IP GTM
    Controller on which this script is run.  The configuration will be
    replaced with the configuration of the remote BIG-IP GTM Controller
    in the specified sync group
    The local BIG-IP GTM MUST already be added in the configuration of the
    other GTM.

    Are you absolutely sure you want to do this? [y/n] y

    ==> Running 'bigstart shutdown gtmd' on the local system
    ==> Running 'bigstart shutdown zrd' on the local system
    ==> Running 'bigstart shutdown named' on the local system
        Retrieving remote and installing local BIG-IP's SSL certs ...
    Enter root password if prompted
    Password:
    Rekeying Master Key...
    Verifying iQuery connection to 100.100.100.10. This may take up to 30 seconds

    Is big3d running?
    Is tcp port 4353 access allowed?

    Restarting gtmd
    Restarting named
    Restarting zrd


    [root@bloor-f5g1:Active:Standalone] config  /usr/sbin/big3d -v
    /usr/sbin/big3d version big3d Version 11.6.0.4.0.420 for linux

    Existing Sync Group member: 
    [root@cammon-f5g1:Active:Standalone] bin  /usr/sbin/big3d -v
        /usr/sbin/big3d version big3d Version 11.4.1.685.0 for linux

 iQuery port is open between the GTMs. 
  [root@bloor-f5g1:Active:Standalone] config  telnet 100.100.100.10
Trying 100.100.100.10...
Connected to 100.100.100.10.
Escape character is '^]'.

lhfhgsjhh

Connection closed by foreign host.

I'm issuing the command 'gtm_add X.X.X.X'on my remote GTM, where X.X.X.X is the IP address of my existing sync group member.

Please suggest where could be the issue and let me know the fix. FYI.. The iquery port is open between the GTMs.

thanks.