Problem of Duration: type is date and time or integer?

I just create one attribute named Duration for a object, I need to choose the type of this attribute, when I choose integer, it always shows me the error. But if I choose the date and time, it works, but when I need to calculate the end date that the function use this duration and start date, it can’t work. so do you know how to solve this problem? please kindly find the below screenshot for the error message.  
1 answers

It depends on what you want to show. I often use decimal to show the duration in seconds (Or minutes, hours,...). You can also choose integer but it will be a little less accurate. It really depends on your usecase.


If integer is throwing an error, you may set it wrong. How do you calculate the duration?