Can't get Campaign IDs or related leads through API

Can't get Campaign IDs or related leads through API

I'm interested in getting the leads assigned to a campaign through the API. According to the documentation, this is possible:

https://www.zoho.com/crm/help/api/getrelatedrecords.html#To_fetch_Leads_related_to_a_Campaign

However, I'm not able to get any data from the call, even though there are leads associated with this campaign:

https://crm.zoho.com/crm/private/xml/Leads/getRelatedRecords?newFormat=1&authtoken=ABCD&scope=crmapi&parentModule=Campaigns&id=1234

  1. <response uri="/crm/private/xml/Leads/getRelatedRecords">
    <nodata>
    <code> 4422 </code>
    <message> There is no data to show </message>
    </nodata>
    </response>

Furthermore, I'm not able to easily get Campaign IDs through the API:

Works:
https://crm.zoho.com/crm/private/xml/Leads/getRecords?authtoken=ABCD1234
https://crm.zoho.com/crm/private/xml/Contacts/getRecords?authtoken=ABCD1234

Doesn't Work!

I get the same error: 4422 with no data to show. In Zoho it shows me 12 different campaigns.

Any suggestions?