Airport entry into Armenia SHOULD be foolproof. Indeed they have the facilities to take your picture on arrival and issue a visa on site. The cost at writing this is presently 15.000 Armenian Drams (about $50 USD). Now both on arrival or when departing the airport beware fully that there has been a rash of corrupt circumstances as to the validity of your passport, the actual dates on your visa with respect to arrival and departure and what all. What YOU need to know it is likely you are being shaken down for a small contribution in order that the circumstances of your papers are acceptable. The unwritten rule is the airport is notorious for this and the airlines don't do much to step in and help. You will need to determine the reality of your situation and take a stand. Usually the officials will back off but when a stern officer says you will need to visit the police office on site you know the game is likely on. Be wary but give quarter there is really nothing wrong with your papers. The object of the exercise is remain calm, act very much like a bewildered tourist. Chances are their frustration that you do not understand the 'envelope' language will have them simply re-stamp and send you on your way. JUST be sure to remember flights arrive in the 3 AM timeline and leave much the same. This is to save on Airport Fees for the carriers. For you the traveler it is tiresome and as a new arrival in a new country at an odd time of the day you are going to wonder your fate. DON'T lose it. Simply stick to your guns as long as you are absolutely sure your paperwork is correct and matches your air ticket dates of arrival and departure. A great smile works wonders. Leave your wallet in your pocket.