Sharing parameters between intents - dialogflow-es

Question

I'm a beginner on dialogflow so maybe what I'm trying to archieve has some concept problem. I have two Intens: "Show options" and "Validate options". The context "ShowOptions" is configured as output on the intent "Show options" and as an input on the intent "Validate options". On the fulfillment functions I'm just trying to add a parameter on the context and when the "Validate options" intent is invoked I'm trying to get that parameter. When the "Validate options" intent is invoked I get an error an nothing is returned. I don't know what I'm doing wrong. This is the code of my fulfillment:
'use strict';
const functions = require('firebase-functions');
const {WebhookClient} = require('dialogflow-fulfillment');
const {Card, Suggestion} = require('dialogflow-fulfillment');
process.env.DEBUG = 'dialogflow:debug'; // enables lib debugging statements
exports.dialogflowFirebaseFulfillment = functions.https.onRequest((request, response) => {
const agent = new WebhookClient({ request, response });
console.log('Dialogflow Request headers: ' + JSON.stringify(request.headers));
console.log('Dialogflow Request body: ' + JSON.stringify(request.body));
function showOptions(agent)
{
var messageText = 'Some text...';
agent.add(messageText);
agent.setContext({name: "ShowOptions", lifespan: 50, parameters: {options: messageText}});
}
function validateOptions(agent)
{
var optionContext = agent.getContext('ShowOptions');
agent.add(optionContext.parameters.options);
}
let intentMap = new Map();
intentMap.set('Show options', showOptions);
intentMap.set('Validate options', validateOptions);
agent.handleRequest(intentMap);
});
The "Validate options" intent has a parameter called optionName. The Raw API response returns this when the intent "Validate options" is invoked with optionName = "text":
{
"responseId": "3f2048bc-08fc-4fb6-b0c2-45f6cc8abf55-ee7586fb",
"queryResult": {
"queryText": "option text",
"parameters": {
"optionName": "text"
},
"allRequiredParamsPresent": true,
"fulfillmentMessages": [
{
"text": {
"text": [
""
]
}
}
],
"outputContexts": [
{
"name": "projects/project_id/agent/sessions/d44625bf-d6ec-2c4b-e2a3-587c72d88fe0/contexts/showoptions",
"lifespanCount": 5,
"parameters": {
"optionName.original": "text",
"optionName": "text",
"options": "Some text..."
}
}
],
"intent": {
"name": "projects/project_id/agent/intents/55d504fb-cabd-4558-8054-e05177d3b362",
"displayName": "Validate options"
},
"intentDetectionConfidence": 0.53878456,
"diagnosticInfo": {
"webhook_latency_ms": 120
},
"languageCode": "en"
},
"webhookStatus": {
"code": 14,
"message": "Webhook call failed. Error: UNAVAILABLE."
}
}