Your script never sets /away, which is why $away is always $false.
Code:
on *:dialog:away:sclick:5: {
  if ($did(11) != $null) {
    set %away.minutes $did(11) 
  }
  set %away.nick $did(4)
  if ($did(4) != $null) { [color:green]tnick $v1[/color] }
  set %away true
  set %away.reason $$did(2)
  set %away.leftat $asctime(h:nn:sstt)
  scon -atl ame $box(is Away) $box(Reason: %away.reason $+ ) $box(Left At: %away.leftat $+ )
  .timeraway 0 3600 scon -atl ame $box(is Away) $box(Reason: %away.reason $+ ) $box(Left At: %away.leftat $+ )
  [color:blue]away $did(2)[/color]
}
on *:dialog:away:sclick:6: {
  [color:green]nick $mnick[/color]
  set %away.returnat $asctime(h:nn:sstt)
  set %away false
  scon -atl ame $box(is Back) $box(Reason: %away.reason $+ ) $box(Left At: %away.leftat $+ ) $box(Returned At: %away.returnat $+ )
  .timeraway off
  [color:blue]away[/color]
}