Resource Capacity - Over-Allocated Hours & Zero Capcity

Hi,

We are trialling using Resource Plans for each of our projects in Project Server 2013.

Using three resources, all with the same calendar, and not assigned to any other project at all; one resource's total work is 500 hours approx more than the other two resources.

The plan is based on FTE units in Months. The hours suggest this resource is working 60 hours/week, yet the other two resources on the same calendar, with same availability, same % - everything, are on 37 hours/week.

When you look at that resource's availability graph, you see zero capacity, and (obviously) over-allocated.

Any ideas??

Thanks,
Andrew