Get RelatedEvents from Sales Orders - mismatch data type error

Get RelatedEvents from Sales Orders - mismatch data type error

Hi,

I'm trying to get the ACTIVITYID of a related event. The parent module is SalesOrders. The code snippet below keeps producing a error 

Mismatch data type for function get at argument index 1 expected data type BIGINT found dataType STRING

  1. eventResp = zoho.crm.getrelatedrecords("Events","Salesorders",salesOrderIdStr,1,5);
    count = 0;
    for each rec in eventResp
    {
    event = eventResp.get(("ACTIVITYID"));
    count = count +1;
    }
    info event;
    info count;
Anybody have any idea's??

Appreciate any help / suggestions