Resource shows as overallocated but is not

Question

I have a project that has been published to the server (PS2010). When looking at the schedule in Project Pro the resource (a few of them) show the overallocation icon (the red man). When I look at the Resource Usage view the resource has the overallocated
warning icon. Yet when I scroll across to where the hours show red, the hours for all projects and tasks for the time period is less than the resource's maximum capacity for the time period.
Can someone help me understand why a resource could show as overallocated when all tasks for the resource for the time period add up to less than the maximum capacity? I have double checked the calendar being used for the resource is the Standard Enterprise
Calendar.
I have also checked in the Resource Center and the Resource Capacity graph shows as UNDER allocated.
I need to know if this problem could be indicative of a larger problem. We are trying to isolate overallocated resources and get them resolved. If the indicators are incorrect, it will be way more difficult for the PM to resolve.

Answer 1

Well, Project plans minute by minute, though most people don't need that much detail. You check the capacity over a specific time period (week, months) but the overallocation may be on a much smaller level than that.
Let's suppose you're looking for overallocations on the week level. On week 3, you have two tasks of, say, 10 hours each. So both of them together still leave you with free time to work on something else, you are underallocated on the week level. But
what if by any chance, the work is spread in such a way that you have 9 hours of work to do on Monday? Project knows from your calendar you actually can't work more than 8 hours per day, so you're overallocated on Monday. Because of this, you'll be displayed
in bright red in the resource usage view as well as the time period where the overallocation is: week 3. The line "overallocation" though will only display the overallocation for the displayed time period, so nothing will show up because there's no overallocation
on the week level.
Because of this logic, overallocations on the hour level used to be a repeated cause for annoyance, but those don't cause resources to be displayed in red anymore, my thanks to the project team for that.
I'm not sure if this is the reason for your problem, but it'd be the first thing to check. Go to the red time period and keep clicking "zoom in", you might find out what's causing it.
Regards,
Livia