That is the expected behaviour using client and server environment and as such is documented in the Reference Manual (Check Sections 29.2 "Macro Functionality Limitations" and 29.3 "Macro Trigger Limitations"). In short, OnReload, OnOpen and OnPostReload macros will not work when the document is on the server. This is not a bug, is a design limit to avoid further inconsistencies.
You will need to allow some users to access the console (adding them to the Server's local group "QlikView Adminstrators") so they can reload manually a file or create and EDX task should you have Publisher (more in the Server Reference Manual).
I'm sorry if I have not been clear enough. Those triggers located in the Settings menu, Document Properties, Triggers tab will work whenever you open the document using the Desktop, and locally, not connecting to a server. So if you run your copy of QlikView Desktop, open the document and click on reload, that will fire the OnPostReload trigger, and the macro will be executed.
There is no other way than this to make that work. They will not work if you do the reload other than clicking yourself on the menu having the document open. I haven't tested if they work when you schedule a reload in the Windows Task Scheduler calling to
C:\ProgramFiles\QlikView\qv.exe /r C:\DocumentFiles\Document.qvw
or whatever your paths are. But it doesn't make any sense to me having the Server to do that.
Hope that helps.