Lambda Function to Connect to AWS IoT and Publish MQTT Messages

Hi I was trying to develop a lambda function which will connect to the AWS thing and publish an MQTT message, I want to receive these published messages on a raspberry Pi which is connected to the thing as well, and subscribed to the same topic. I managed to create the thing, certificate and connect to it. But the lambda function seems to not send the MQTT message. I am attaching my sample code here in the index.js. I kept all my certificates and keys in a folder and zipped and uploaded. Since I am testing this lambda function now, I am not using the event to trigger the connection and message publishing, I just did it like whenever the function is called , it will connect and publish the message. The function seems to be running without error, but I dont see any message coming to my Pi when this runs, (I have a python code running at the Pi side which is subscribed to the same topics, and it is connected to AWS as well). Below is the lambda code I am using, could anyone please help me if I am missing something here ?

var awsIot = require('aws-iot-device-sdk'); var deviceName = "Bibin_Pi_3"; // Updated by Bibin from AWS IOT Thing name

var thingShadows = awsIot.thingShadow({ keyPath: './private.pem.key', certPath: './certificate.pem.crt', caPath: './rootCA.pem', clientId: deviceName, region: "eu-east-1", });

var ctx = null;

exports.handler = function (event, context) { ctx = context;

thingShadows.on('connect', function() {
		thingShadows.register(deviceName);
		console.log("Connected...");
        console.log("Registering...");

	});
	
	thingShadows.on('message', function(topic, payload) {
        console.log('message', topic, payload.toString());
    });

thingShadows.publish('qrio/test/pi/voice', 'BedroomLightOn', function(){
		var cardTitle = "Bedroom Lamp on";
		var repromptText = "";
		var sessionAttributes = {};
		var shouldEndSession = false;
		var speechOutput = "Your bedroom light is on. ";
		repromptText = "Your bedroom light is on. ";
		var shouldEndSession = false;
		
	});
	console.log('value1 =', 'Bibin');
	ctx.succeed();

};