Map layers don't appear

I've nearly got the module working, after enabling allow_url_fopen. The server connects to the sample NASA wms server and I select some different layers. I configure the view as noted in the doc and video.

However, the resulting view will only show a blank space where the map layer should be, with my sample node otherwise correctly displayed (except that it's waaaay over on the left). See the screenshot.

I've played with many of the layer selections, but it doesn't seem to matter. I do notice when I view source that the width is set to 0 no matter what the size configuration in the view (but height is carried over perfectly), which seems odd:

<div class="view-content">
      <div>
 
    <div  class="nicemap-map" style=" width:0; height:400px;">
      <a href="http://mysite.org/content/test1" class="geopoint " style="left: 64.665%; top: 47.153825%;" id="geopoint-0"><span>Test1</span></a>
      <div class='hidden'><div class='geoitem' id='geoitem-0'><span class='close'>Close</span> </div></div>

Am I missing something obvious?