Code:
 
alias channelkill {
  if ($left($1,1) !== #) {
    echo -a Channel Kill Error: First parameter is to be a channel!
  }
  elseif ($2 == $null) {
    echo -a Channel Kill Error: Second parameter must be filled with a reason!
  }
  else {
    echo -a Channel Kill Command Success
  }
}

First when I try to test the first if
/channelkill Test
=
Channel Kill Error: First parameter is to be a channel!
Which is correct
Then when I try to test the elseif
/channelkill #Test
=
Channel Kill Error: First parameter is to be a channel!
And even if I do the whole command right
/channelkill #Test Hi
Channel Kill Error: First parameter is to be a channel!