https://campaigns.zoho.com/api/addlistsubscribersinbulk ?authtoken = ****

I am giving authentication code along with scope =CampaignsAPI, my campaign list key . but i am getting the following respose  <code>Z101</code><status>error</status><message/></response> where i have found the support for this error nowhere. 

The quick response on this  would be highly appreciated appreciate