There are a number of possible reasons why Pinnacle may not calculate depreciation for an asset:
The asset is marked as not being depreciable. Open the asset and check that the Depreciable box on the Financial tab is checked.
The asset has a depreciation rate of zero percent. This can be amended by using Pinnacle's asset financial adjustment functions.
The asset has a delivery date which is in the future. The delivery date is the date from which Pinnacle calculates depreciation.