Add calculated number of hours to date

Add calculated number of hours to date

I'm not very much into Deluge yet, so I am having a little bit of trouble of with below, where the ultimate goal is to add a calculated number of hours to a date specified in the form. 

My first five lines works fine, but the last do not return a value. (I.e. 16-05-2016 12:00 + 72:00 hrs = 19-05-2016 12:00)

input.Ops_Time1 = ((input.Reporting_Time - input.Operations_Commenced)  /  (1000  *  60  *  60)).round(1);
input.Moves_Performed = (input.Units_Discharged  +  input.Units_Loaded);
input.Moves_Remaining = (input.Remaining_for_Discharge  +  input.Remaining_to_Load);
input.Productivity = (input.Moves_Performed  /  input.Ops_Time1);
input.Time_Remaining = (input.Moves_Remaining  /  input.Productivity);
input.ETC = Operations_Commenced + addHours(Time_Remaining);