Farah Diana Masri I'm glad that your issue is resolved and thank you for posting your solution so that others experiencing the same thing can easily reference this!
Since the Microsoft Q&A community has a policy that the question author cannot accept their own answer, they can only accept answers by others, I'll repost your solution in case you'd like to Accept the answer.
Error Message:
Currently, I have issues to consume the image prompt flow endpoint. I have followed this guide to create image prompt flow and deploy it. I try to consume this endpoint in the Postman for testing. But I receive these 2 responses, first one can analyze but second one couldn't analyze. I use the same method to call the endpoint, but why the one response can analyze but another one could not?
Solution:
It is because the format of the request being sent actually.
If you have any other questions, please let me know. Thank you again for your time and patience throughout this issue.