getRelatedRecords not working while getRecords is working

getRelatedRecords not working while getRecords is working

So i have the following code that gets all the records ( at least the first 200 ) of my custom module:

notificationLines = zoho.crm.getRecords("Notification_Lines", 1, 200 );
for each notificationLine in notificationLines{
     //info notificationLine;
}

>> This is working fine, but:

Now, the second step is to get the records related to the selected lead:
relatedNotificationLines = zoho.crm.getRelatedRecords("Notification_Lines","Leads", leadID);
for each relatedNotificationLine in relatedNotificationLines{
     info "Test : " + relatedNotificationLines;
}

But I get the following error:
Test : {"code":"INVALID_DATA","details":{},"message":"the relation name given seems to be invalid","status":"error"}

Can someone help me on this?

This is the related list in my lead account: