Linking a new lead to a campaign in custom function

Linking a new lead to a campaign in custom function

while using the zoho custom function ( code is bellow )

campId = "xxxxxxx";
mp = Map();
mp.put("Campaigns",campId.toLong());
resp = zoho.crm.updateRelatedRecord("Campaigns",campId.toLong(),"Leads",leadId.toLong(),mp);
info resp;

it executes but showing the given error

{"code":"INVALID_DATA","details":{},"message":"the relation name given seems to be invalid","status":"error"}

can you guyz help me out