Why can't I summarise durations in a chart in a interface?

[Kim_Trager1]

I've been scratching my head to why this is not possible, and I still have a feeling I'm doing something wrong but I can't figure out what.

I have a bunch of time logs that has been logged over multiple years. Every log has an item linked to them which has a rollup that assign every time log into a category based on the item.

My data looks like this:

 In the interface designer I want a bar chart that summarises all this data.

The X-axis should be the years, then the Y-axis should be the amount of time spent.

Each bar should be a total of time spend in that year. Then each bar should further be divide into the rollup categories.

I've set the sourse to Costing tab, and the X-axis to Years

The field I'm summarising is the Time field - which is a duration input field

In the aggregate I can't choose Sum

However when I try to summarise the inputted times, every option except from distinct is greyed out - why can I not choose fx the Sum or the Average, which I find weird as a Time input surely is just a bunch of numbers, and its not being computed in a formular field?

[Maya_Bialik]

Same issue

[jessica]

Same issue

[Marc_Weldon]

Worked this one out. It's because the field you're trying to summarise is a duration, not a number. If you create a new formula field to make it a number (we use this a lot for time fields, just call the column the same thing and add 'DISPLAY' to the field name), by using the field *3600 (as duration fields are stored as number of seconds) then you have a normal number to report on, and then should be able to summarise with SUM etc.