API v2 campaign listing

API v2 campaign listing

Hi,
I would like to use the API to retrieve the campaigns created.
I have already been able to retrieve the accounts and contacts using the index but I am not sure how I should do for the campaign. I receive the error message "INVALID MODULE". 

here is my get:
https://www.zohoapis.com/crm/v2/Campaign

Thanks for the help!