Hi Jin,
I don't study this period, but your item is surely a pre-philatelic cover.
Dentecane is a district of Pietradefusi, a town in province of Avellino (Campania, Italy, not so far from Naples). The postmark of Dentecane is the classical postmark of pre-philatelic period. But it's the other postmark to help us about the date, because the ''Real Servizio'' postmark is a 'must' of pre-philatelic period of the Two Sicilies Reign. Since 1820, the 115 offices of the Reign used to mark the covers with the normal postmark of the town (in your case, Dentecane) and, usually, with another postmark referred to the service, ''Real Servizio'' ( = ''Royal Service''), ''Franca'' ( = ''Franked'') or ''Assicurata'' ( = ''Insured'').
Your cover is postmarked by ''Real Servizio'' because was shipped by ''mastro di posta'' (post office director) of Dentecane to General Director of Reign Post, in Naples; the general direction was in fact established in Naples.
These postmarks were used for 40 years, at least till 1860, so, only by these elements it's impossible to assign a date to your cover. Probably, a specialist of local post of Naples environments could be more useful.
Here is a very similar cover, shipped on 1860.
Allegato:
real_servizio.jpg [ 14.85 KiB | Osservato 12157 volte ]
