I believe its cmd that breaking the symbol, not kix (see sample below that works). Any reason why you don't build the query line and then run it in kix instead of writing it to a separate cmd file?

 Code:
$nul = Open(1,@ScriptDir+"\test.txt",5)
$nul = WriteLine(1,"Francis Bossé")
$nul = Close(1)

$nul = Open(1,@ScriptDir+"\test.txt")
? readline(1)
$nul = Close(1)

get $