Problems testing eventGrid topic.

I've created an eventGrid topic in my enterprise's subscription and when i try to send a message with postman i'm obtaining this error

{
    "error": {
        "code": "InternalServerError",
        "message": "An unexpected error has occurred. Please report the x-ms-request-id header value to our forums for assistance or raise a support ticket. Report '570575de-87a5-472c-96f3-8eb7bbb595a4:9/16/2018 4:07:19 PM (UTC)' to our forums for assistance or raise a support ticket.",
        "details": [{
            "code": "UnexpectedError",
            "message": "An unexpected error has occurred. Please report the x-ms-request-id header value to our forums for assistance or raise a support ticket. Report '570575de-87a5-472c-96f3-8eb7bbb595a4:9/16/2018 4:07:19 PM (UTC)' to our forums for assistance or raise a support ticket."
    }]
  }
}

The request id is:

x-ms-request-id →570575de-87a5-472c-96f3-8eb7bbb595a4

What am i doing wrong? Thanks in advance for the support.