Help with connecting REST API with OpenAI endpoint

Summary:

Connection to OpenAI API endpoint from REST API is not working. I have used the correct authentication bearer token, correct model name, but continue to get 404 error

Content (please ensure you mask any confidential information):

Error: cloudinvocationexception

{
"error": {
"message": "The model gpt-4 does not exist or you do not have access to it.",
"type": "invalid_request_error",
"param": null,
"code": "model_not_found"
}

Version (include the version you are using, if applicable):

Code Snippet (add any code snippets that support your topic, if applicable):