Null/Empty Chunks while invoking an agent

Hi Everyone , I am trying to invoke bedrock agent via below code from a Lambda function

def call_agent(input_data):
    print("Invoking Agent")
    client = boto3.client('bedrock-agent-runtime')
    agent_arn = '<AGENT_ARN>'
# Call the Bedrock agent
    agent_response = client.invoke_agent(
        agentAliasId = '<AGENT_ALIAS>',
        agentId = '<AGENT_ID>',
        enableTrace = True,
        inputText = input_data,
        endSession = False,
        sessionId = str(uuid.uuid4())
    )
    print("RAW Response :", agent_response)
    
    if 'completion' not in agent_response:
        raise ValueError("Missing 'completion' in agent response")
        
    for event in agent_response['completion']:
        if 'chunk' in event:
            data = event['chunk']['bytes']
            decoded_bytes = data.decode('utf8')
            print('bytes: ', decoded_bytes)
            message = message + decoded_byte
        else:
            raise ValueError("Missing 'chunk' in agent response")
    return message

I am getting Missing 'chunk' in agent response with any input . Can anyone help with why I am getting null chunks ?

Below, I have shared the response of invokeAgent API

RAW Response : {'ResponseMetadata': {'RequestId': '2e0d0d4a-1b08-4531-8c55-8864bf387538', 'HTTPStatusCode': 200, 'HTTPHeaders': {'date': 'Tue, 20 Aug 2024 06:16:42 GMT', 'content-type': 'application/json', 'transfer-encoding': 'chunked', 'connection': 'keep-alive', 'x-amzn-requestid': '2e0d0d4a-1b08-4531-8c55-8864bf387538', 'x-amz-bedrock-agent-session-id': '399068f7-a518-40c7-97a3-db21c9b8ebb9', 'x-amzn-bedrock-agent-content-type': 'application/json'}, 'RetryAttempts': 0}, 'contentType': 'application/json', 'sessionId': '399068f7-a518-40c7-97a3-db21c9b8ebb9', 'completion': <botocore.eventstream.EventStream object at 0x7f5d93a74f80>}