Did you try typing 'bind my soul'?  It works for me with the generic script.
Otherwise, you might need to provide more detail - which soulbinder are you talking to in game (name and zone), in the quests folder for that zone does the soulbinder have a script, if so is it referencing the soulbinder script in the quests/plugins folder?
Using Soulbinder Jera in plane of knowledge as an example:
	Code:
	# /quests/poknowledge/Soulbinder_Jera.pl
#generic soulbinder quest
sub EVENT_SAY { 
	plugin::soulbinder_say($text);
}
 
	Code:
	# /quests/plugins/soulbinders.pl
sub soulbinder_say {
	my $text = shift;
	if($text=~/hail/i){
		quest::say("Greetings ${name} . When a hero of our world is slain their soul returns to the place it was last bound and the body is reincarnated. As a member of the Order of Eternity  it is my duty to [bind your soul] to this location if that is your wish.");
	} elsif($text=~/bind my soul/i) {
	    quest::say("Binding your soul. You will return here when you die.");
	    quest::selfcast(2049);
	}
}