Custom_Vision_Prediction_3.0 REST API Giving 401 error

I am trying to call Custom Vision Prediction Classification RestAPI Endpoint (https://southcentralus.dev.cognitive.microsoft.com/docs/services/Custom_Vision_Prediction_3.0/operations/5c82db60bf6a2b11a8247c15)

I am using South Central US endpoint

I got the required Training and Prediction key from Keys section In Resource Management Azure Portal

Following is the response I am getting back if I call the Custom Vision Prediction classification RestAPI Endpoint

{

"error": {
"code": "401",
"message": "The ClassifyImage Operation under Custom_Vision_Prediction_3.0 API is not supported with the current subscription key and pricing tier Custom_Vision.Training.S0."
}
}

I can see that It saying that my current pricing tier is not supporting 3.0 API but the plan S0(Standard) costing me 0.35 USD per 1k images and my subscription plan is Pay-As-You-Go

Then Why I am getting this error?

Any help appreciated

When you create a Custom Vision in your Azure subscription, two resources are created for you: One for Training and one for Prediction. Each has a dedicated set of API keys.

Make sure to use the correct resource for either Training or Prediction usage.