facebook Marketing API error 803 c#

Question

trying to do https://developers.facebook.com/docs/marketing-api/buying-api
the token is a sandbox token
getting error:{"error":{"message":"(#803) Some of the aliases you requested do not exist"
is an account id error
i got the account id from :https://www.facebook.com/adsmanager
i even tryd my facebook page id or an app id from :https://developers.facebook.com/apps/

not sure what else to try anyone know how to deal with this error?

static void Main(string[] args)
    {

        string test = postrequestAsync().GetAwaiter().GetResult();


        Console.WriteLine(test);
    }

    private static async System.Threading.Tasks.Task<string> postrequestAsync()
    {

        /*
         'name=My campaign' \
          -F 'objective=LINK_CLICKS' \
          -F 'status=PAUSED' \
          -F 'access_token=<ACCESS_TOKEN>' \
          https://graph.facebook.com/v3.0/act_<AD_ACCOUNT_ID>/campaigns


         */

        try
        {
            var values = new Dictionary<string, string>
        {
           { "name", "My campaign" },
           { "objective", "LINK_CLICKS" },
           { "status", "PAUSED" },
           { "access_token", token }
        };

            var content = new FormUrlEncodedContent(values);

            var response = await client.PostAsync("  https://graph.facebook.com/v3.0/act_<"+accountid+">/campaigns", content);

            var responseString = await response.Content.ReadAsStringAsync();
            return responseString;
        }catch(Exception e)
        {
            return e.Message;
        }
    }