Hello Jenny,
Thank you for posting on the Microsoft Dynamics NAV Forum. There are many possibilities for why Depreciation isn't calculated. The link to the detailed help for Fixed Assets is at the following (for NAV 2016 - but 2017 is very similar if not identical):
https://docs.microsoft.com/en-us/previous-versions/dynamicsnav-2016/hh165398(v=nav.90)
You may need to begin with the general setup in Fixed Asset (FA Setup) Setup.
The other key setup is Depreciation Books. This is where you can define your Financial (Company Book) and possibly a Tax Book if you are trying to calculate Tax Depreciation as part of your NAV/BC Fixed Assets. There could be an AMT book, as well. It all depends on how much of the required Fixed Asset calculations you are trying to manage within your Dynamics NAV 2017 system.

Before depreciation is calculated, you would need the following:
1) Each asset setup with a Fixed Asset Card and relevant details.
2) Assign Depreciation Method for the primary "Company Book" (discussed above) - the Depreciation Method and Useful Life (Or Depreciation Percentage if Declining Balance is used) are required for the system to calculate depreciation. (Exception would be if a User Defined Depreciation Method is selected and User defined Depreciation Table is created.)
3) Depreciation Starting Date (Ending Date will be automatically populated based on Useful life) - typically same as Acquisition Date but not always if that asset is acquired but not placed in service - must be established.
It will look something like this:

4) Acquisition Cost (Posting Date of original Acquired Date) and Accumulated Depreciation (Negative amount posting - can be posted in total through last depreciation date in the Trial Balance). The beginning values for these are posted either through FA G/L Journal if the Company Book is Integrated to the G/L or posted through FA Journal if Integrated is unchecked.
[ Note, during initial implementation, Integration may be deselected on the Depreciation Book (See above screen shot for Company Depreciation Book) because the G/L Entries for the beginning Trial Balance already have the Fixed Asset Acquisition Cost and Accumulated Depreciation balances established as part of posting a General Journal. In that case, Integration is temporarily deselected so that there is no duplicated impact to the Trial Balance. When this is done, the initial Acquisition Cost and total beginning Accumulated Deprecation are posted through FA Journal (NOT FA G/L Journal). This establishes the correct totals at the subsidiary Fixed Asset Ledger that should match in total to the beginning Trial Balance. Once this initial balance posting for all assets is completed, then the primary Company Depreciation Book can be updated with Integration enabled so that future Acquisitions, Depreciation, and other transactions posted to the Fixed Assets will be autoamtically integrated to the G/L Entries and update the required ledgers simultaneously. ]
Some additional general setup to consider:
1) Accounting Periods - Make sure your Accounting Periods are defined out into the future several years - particularly if you plan on reviewing the FA Projected Value report. The periods help define the fiscal year for the company and are used by the Depreciation Method and related configuration for each asset.
2) Depreciation Tables - These are used for User Defined Depreciation, which works well for MACRS Tax Tables to be setup.
Additional Key Information:
After running the Calculate Depreciation process, you will need to go to either the FA G/L Journal (If Depreciation Book is Integrated = Yes) or the FA Journal (if not integrated). This may be the other reason you are not seeing depreciation. The Calculate Depreciation populates the appropriate Journal to be reviewed and then posted. The Calculate Depreciation doesn't automatically record the FA Ledger and update the G/L Entries directly. The Journal must be reviewed and posted separately.
These are some things to consider when analyzing the issue. Hopefully, the provided information and link to detailed On Line Help will move you forward.
Have a great day.
Best Regards,
Tom