This message indicates that the specified ticker is not allowed on this webhook. You can control what tickers are allowed on a webhook with the Asset class, Allow any ticker and Tickers field when editing your webhook.
Asset class - This is the asset class that the webhook is allowed to receive. If the ticker is not in the asset class, it will not be allowed.Allow any ticker - If this is checked, the webhook will allow any ticker within the configured asset class. If this is not checked, the webhook will only allow tickers that are in the Tickers list.Tickers - This is a list of tickers that the webhook is allowed to receive. If the ticker is not in this list, it will not be allowed.For example, if you have you have Allow any ticker unchecked and Tickers is set to AAPL, MSFT, GOOGL, the webhook will only allow those three tickers. If you try to send a webhook with a ticker that is not in that list, you will get this error message.