I have run the Capacity vs Demand by Resource, when the filter Unit type is Hours then Capacity and Demand shows some numbers.
When I pass FTE Capacity and Demand is Zero, how this report works ?
There is one defect (DE34301) I'm aware of you could be hitting, depending on your PPM version (See: CA PPM: Zeroes are displayed for the Available FTE - CA Knowledge ) This defect is fixed in 15.3 (and 15.2 patch 3).
This defect is not what is problem defined, the defect is for adhoc reports using domain but what is asked is for OOTB reports
See if you meeting all the pre requisite for the reports documented here Capacity vs. Demand by Resource - CA PPM - 15.4.1 - CA Technologies Documentation
In this Issue case its 15.2 patch 3