Not able to SEARCH CONTACT over DESK API

Not able to SEARCH CONTACT over DESK API

I am trying to use search contacts over the api, using the endpoint https://desk.zoho.com/api/v1/contacts/search is returned the error 
{
"errorCode": "FORBIDDEN",
"message": "You are not authorized to access this resource."
}

I tried to use AuthToken authentication and also the OAuth with the following SCOPES: Desk.search.READ , Desk.contacts.READ, both returned the error above, but only for the Search resource, any other resource is working fine, I can create Contacts, create Tickets, etc.

any thoughts about what is wrong?