Mjpeg camera not showing up

I copied this from an ORDIOD forum to try out cameras, but nothing shows up on the main page. Is there something else I’m missing? I assume that there are no add-ons needed and just entered the following in my configuration.yaml (I tried it without and with tic marks):

camera:
  - platform: mjpeg
    mjpeg_url: 'http://iris.not.iac.es/axis-cgi/mjpg/video.cgi?resolution=320x240'
    camera1_still_url: http://iris.not.iac.es/jpg/image.jpg
    name: Observatory in Spain    

I removed the ?resolution=320x240 from the string and that did it…