In Meetme.conf

[generals]

[rooms]
conf => 555


In extension.conf

exten => 555,1,MeetMeCount(555,CONFCOUNT)
exten => 555,2,GotoIf($[${CONFCOUNT} <= 2]?3:100)
exten => 555,3,MeetMe(555)
exten => 555,100,Playback(conf-noempty)


But When I dial 555 than Its says wrong number and in asterisk -r it shows me 

-- Executing [555@default:1] MeetMeCount("SIP/harpal-081d3168", "555|CONFCOUNT") in new stack
  == Parsing '/etc/asterisk/meetme.conf': Found
    -- Executing [555@default:2] GotoIf("SIP/harpal-081d3168", "1?3:100") in new stack
    -- Goto (default,555,3)
    -- Executing [555@default:3] MeetMe("SIP/harpal-081d3168", "555") in new stack
  == Parsing '/etc/asterisk/meetme.conf': Found
[Nov 23 16:46:32] WARNING[20558]: app_meetme.c:772 build_conf: Unable to open pseudo device
    -- <SIP/harpal-081d3168> Playing 'conf-invalid' (language 'en')
  == Spawn extension (default, 555, 3) exited non-zero on 'SIP/harpal-081d3168'