I will test that after my ISP puts it in DNS , can you tell me why is only my primary domain signatured with DKIM and other domains are sent without DKIM ?

Yes this is from conf :

$enable_db = 1;              # enable use of BerkeleyDB/libdb (SNMP and nanny)
# $enable_zmq = 1;           # enable use of ZeroMQ (SNMP and nanny)
$nanny_details_level = 2;    # nanny verbosity: 1: traditional, 2: detailed
$enable_dkim_verification = 1;  # enable DKIM signatures verification
$enable_dkim_signing = 1;    # load DKIM signing code, keys defined by dkim_key

@local_domains_maps = ( [".$mydomain","xxxxxx.yy","xxxxxx.zzz"] );  # list of all local domains

@dkim_signature_options_bysender_maps = ( {
    # ------------------------------------
    # For domain: xxxx.yy.
    # ------------------------------------
    # 'd' defaults to a domain of an author/sender address,
    # 's' defaults to whatever selector is offered by a matching key

    #'postmaster@xxxx.yy'    => { d => "xxxx.yy", a => 'rsa-sha256', ttl =>  7*24*3600 },
    #"spam-reporter@xxxx.yy"    => { d => "xxxx.yy", a => 'rsa-sha256', ttl =>  7*24*3600 },

    # explicit 'd' forces a third-party signature on foreign (hosted) domains
    "xxxx.yy"  => { d => "xxxx.yy", a => 'rsa-sha256', ttl => 10*24*3600 },
    #"host1.xxxx.yy"  => { d => "host1.xxxx.yy", a => 'rsa-sha256', ttl => 10*24*3600 },
    #"host2.xxxx.yy"  => { d => "host2.xxxx.yy", a => 'rsa-sha256', ttl => 10*24*3600 },

# catchall defaults
    '.' => { a => 'rsa-sha256', c => 'relaxed/simple', ttl => 30*24*3600 },