Trouble creating Q Business app via Python SDK

Hey all:

I am trying to create a simple Q app via the API from Python. When I run the below code, I get the following error:

An error occurred (AccessDeniedException) when calling the CreateApplication operation: Identity Type can not be null.

Here's the code:

import requests
import json
import boto3

# Initialize a Boto3 client for Amazon Q
aws_service = 'qbusiness'
client = boto3.client( aws_service )

# Parameters for the application creation
params = {
# "attachmentsConfiguration": {"attachmentsControlMode": "string"},
# "clientToken": "string",
# "description": "string",
"displayName": "pmo-q-bot-py-test",
# "encryptionConfiguration": {"kmsKeyId": "string"},
"roleArn": "arn:aws:iam::999999999999:role/aws-service-role/qbusiness.amazonaws.com/AWSServiceRoleForQBusiness",
# "identityCenterInstanceArn" : "",
# "tags": [
#     {"key": "string", "value": "string"}
# ]
}
# Create the application
try:
    response = client.create_application(**params)
    # Print the response
    print(response)
except Exception as e:
    print( e )

Nothing in the docs defers to an Identity Type being part of a Q business app. Might it be related to the user and role I'm using? (Authentication is via keys stored in the local config files).

Any thoughts?

Thanks, Steve