on *:TEXT:!checkz:#: {
  var %c = 1
  while ($read(Blacknickstotal.txt, %c) <= 21) && ($read(Blacknickstotal.txt, %c) > $read(totalscheck.txt, 1)) { 
    write -l1 totalscheck.txt $read(Blacknickstotal.txt, %c)  
    inc %c 
  }
}

In variables %c = 4
And the 4th line is the largest number, however, it isn't writing it to totalscheck.txt