can't get evergreen to run tests

[kenirwin]

Hi -- I'm trying to get my first Evergreen installation to run with a simple test, and I'm stuck. I hope you can help.

When I got to 127.0.0.1/evergreen, I can see my test, but when I click "Run", I just get a swirly icon as if it's waiting for something to load.

Here's what I've done:
I've installed Evergreen 1.2.0, and the rake -T spec returns:
rake spec:javascripts # Run JavaScript specs via Evergreen

Following along with the CodeSchool screencast on Jasmine/CoffeeScript testing with Evergreen:
https://www.codeschool.com/screencasts/testing-coffeescript-with-jasmine
I wrote a single test in spec/javascripts/demo_spec.js:
myApp = {}
myApp.Calculator = {
add: (a,b) -> a + b
}

describe 'A Calculator', ->
it 'should add two numbers', ->
result = myApp.Calculator.add(2,3)
expect(result).toEqual(5)

I ran 'evergreen serve'
Went to 127.0.0.1/evergreen and clicked 'Run', and all I get is the spinning icon, with no tests run.

Do you have any suggestions about what I need to do to get a test to run?

Thanks!