Call to watson conversation service failed

I'm a newbie to node-red so please bear with me if I'm asking stupid questions.
I'm creating a slackbot using watson assistant. In the process, I have to configure my assistant node with the credentials given in the watson assistant website.
I have configured like this:

On invoking a slash command, I get the following error on the assistant node - 'Call to watson conversation service failed'

and the following error on the debug console which also corresponds to the assistant node -

"context": {
"requestId": "fa474ea494af46768f0ef069140c1d58",
"requestType": "incoming.Identity_Token",
"userAgent": "NotSet",
"clientIp": "",
"url": "",
"instanceId": "iamid-3.9-5632-fbeedc3-7cf859bc99-5d6k7",
"threadId": "219c6d",
"host": "iamid-3.9-5632-fbeedc3-7cf859bc99-5d6k7",
"startTime": "22.04.2019 10:55:41:484 UTC",
"endTime": "22.04.2019 10:55:41:568 UTC",
"elapsedTime": "84",
"locale": "en_US",
"clusterName": "iam-id-prfra02-1m5r"
"errorCode": "BXNIM0415E",
"errorMessage": "Provided API key could not be found"

Can someone please help me with this.

If you are using a node you have installed it’s always worth including the name of the node you are using in your post.

It’s also worth including the version of Node-RED and nodejs you are using, this are both printed in the messages when node-RED starts.

If you are running Node-RED on bluemix or another cloud platform it’s worth stating that as well.

I'm sorry. Thanks for correcting me.
I have used watson-conversation-v1 node which was there by default (I didn't install it).
The Node-RED version is v0.20.3 and the nodejs version is 6.x.
I'm running Node-RED on IBM Bluemix.

Node-RED v0.20.x requires nodejs v8 or later so the first thing you need to do is to change the version of nodejs you are using.