Problem with jquery ajax call and js.rjs code

On one of my pages, i make a remote request to the update action of my school_subscribers controller with a jquery ajax call.

In my log, i can see that the action executes fine, and the corresponding js.rjs file is evaluated (i'm logging from inside that file and it all seems fine). I can see in the firebug console that i get a 200 back from the remote request. But, the code in the js.rjs file isn't actually executed. I tried the simplest possible case of having it just do

page.alert("hello")

but no joy.

I think that this is just a problem with how i have my jquery ajax options set up - possibly the datatype option. I tried omitting datatype, and setting it to 'script', or 'html' but neither worked.

here's my call:

    function updateSubscriber(id, paramString){       jQuery.ajax({         async:true,         type: "PUT",         datatype: 'script',         url: "/music_service/"+<%= @music_service.id %>+"/school_subscribers/"+id,         data: (paramString),         error: function(msg){           alert("Sorry, there was an error updating this subscriber");         }       });     }

Can anyone see what i'm doing wrong? Should i be using an ajax call in this case?