ember template can't find my custom helper

I created a helper called graph-helper.coffee which will compile to js. When it compiles, it successfully creates the js copy of the helper graph-helper.js, but in my template, when I do the console tells me:

"Assertion Failed: A helper named "graph-helper" could not be found"
name

here is my coffee file

Ember.Helper.helper (params) ->
arg1 = parseFloat(params[0]);
arg2 = parseFloat(params[1]);

return arg1 * arg2;