API configuration.export of images does not work as documented

The API method configuration.export accepts the parameter "option" with the objects to be exported.

The options object has the following parameters according to the documentation:
groups - (array) IDs of host groups to export;
hosts - (array) IDs of hosts to export;
images - (array) IDs of images to export;
maps - (array) IDs of maps to export.
screens - (array) IDs of screens to export;
templates - (array) IDs of templates to export;

When trying to export an image with this method, the result is not the expected one.

Trying to get an image with this code (or any other existing imageID):

{"jsonrpc":"2.0",
 "method":"configuration.export",
 "params":{
    "options": {
         "images": ["156"]
      }, 
      "format": "json"
  },
  "auth":"2847454aaa55a9abf354db9ded233e49",
  "id":1}

Will always return this:

{"jsonrpc":"2.0",
 "result":"{\"zabbix_export\":{\"version\":\"2.0\",\"date\":\"2014-11-05T16:15:59Z\"}}","id":1}

It looks like the method can not find the image with the imageID.

The other objects groups, hosts, maps, screens and templates work as expected.