Insert experiment to Google analytics api (gapi)

Question

I'm trying to insert an experiment to Google analytics through their api (using gapi)

var experiment = {
  "name": "Testing",
  "description": "test",
  "status": "READY_TO_RUN",
     "variations": [{
        "name": "Original",
        "url": "http://abc.se",
      }, {
        "name": "Variant 1",
        "url": "http://abc.se/1",
      }],
};

gapi.client.analytics.management.experiments.insert({
  'accountId': currentProfile['accountId'],
  'profileId': currentProfile['profileId'],
  'webPropertyId': currentProfile['webPropertyId'],
  'resource': experiment
}).execute(callback);

The response-code I get is "code": 500, "message": "There was an internal error.",

Any help will be mostly appreciated. (First question on stackoverflow, I apologize in advance if my question is fuzzy.)

Answer 1

The solution was to add the parameter "objectiveMetric". Altough it is not specified in the documentation.

final code:

var requestBody = {
  "name": "testing2", //required
  "status": "READY_TO_RUN", //required
  "objectiveMetric": "ga:goal11Completions", //required?
  "variations": [
  {
   "name": "test1", //required
   "status": "ACTIVE",
   "url": "http://abs.se/3" //required
  },
  {
   "name": "test2", //required
   "status": "ACTIVE",
   "url": "http://abs.se/4" //required
  }
 ]
};


var request = gapi.client.request({
  'path': '/analytics/v3/management/accounts/{accountId}/webproperties/{webPropertyId}/profiles/{profileId}/experiments',
  'method': 'POST',
  'body': JSON.stringify(requestBody)});
  request.execute(handleAccounts);
}

Big thanks to Pete for the help.