Custom function to create event is adding 6hrs to start time?

My custom function works except it is adding 6 hours to the event start time. I've tried various solutions but none have worked. Any suggestions? It's pulling the datetime from a custom field in my Lead record.

The event date/time in my lead record field is named 'Product Demo'. My code is below.

void new_event_demo ( int leadId, date product_demo, string meeting_id, string meeting_url )

leadDetails = zoho.crm.getRecordById("Leads",input.leadId);

start_time=input.product_demo.toTime();

end_time=start_time.addHour(1);

eventMap=map();

eventMap.put("Subject","Web Demo");

eventMap.put("SMOWNERID",ifnull(leadDetails.get("SMOWNERID"),""));

eventMap.put("Start DateTime",start_time);

eventMap.put("End DateTime",end_time);

eventMap.put("Meeting ID",input.meeting_id);

eventMap.put("Meeting Join URL",input.meeting_url);

eventMap.put("SEID",input.leadId);

eventMap.put("SEMODULE","Leads");

createEvent = zoho.crm.create("Events",eventMap);

info eventMap;

info createEvent;