"call_to_action_type field in creative is required in this ad" returned while creating ads using marketing api

When I use adcreatives endpoint with object_story_spec parameter to create ads or using object_story_id parameter following instructions in this link :

I got this error message:

{"error":{"message":"Invalid parameter","type":"FacebookApiException","code":100,"error_subcode":1487664,"is_transient":false,"error_user_title":"Missing Call To Action Type","error_user_msg":"call_to_action_type field in creative is required in this ad"}}

Anyone knows how to solve this problem?