treasures in nightfall

My question is: can the treasure still be farmed? if yes, how much i need to wait until i found something in it? or what i need to do to can reopen a treasure and find something? because i recently buy the nightfall and i opened all the treasures, i waited more than 30 days to reopen one and it drops nothing, now i waited more than two months to reopen other treasure and it drops nothing again, is it a bug? or what i am doing wrong?
my character is from tyria

Treasures can be opened once every month

i know it, the wiki says that, but i wait for more than two months and nothing was inside

then i need to report this like a bug?

dude, farm elsewhere. there is like at least million better places to farm things rly.
As for the treasures... they drop items and gold every month but they may as well not drop a single thing

Because golds and gold is bad.

There are quite a few notes on the wiki page I remember.
http://wiki.guildwars.com/wiki/Treasure

thank everyone for the answers

Josue, just a note: if you try to open a treasure too early, you'll A) get nothing AND B) restart the timer.

I also suspect that you lower the drop quality as if you had opened it on time, but this is just a gut feeling.

Another note, first treasures(at noob isle) will mostly just give purples, and the others further in the game will near always give golds+alot more plat.

They start out giving all gold, and they degrade every time you collect, so eventually you will only get purples and a few gold, etc.

I have been getting treasures in Istan, Kourna and Vabbi for more then a year now with 5 characters.

When u get an item, the first few times u always get a gold, then a purple item.
The amount of gold u get also gets less or after every few times.

I usually wait a little more then 1 month, 5 to 6 weeks.

@OP, next time if u dont get an item do check if u get some amount of gold.
U r supposed to get an item and a gold amount.

Besides a bug, what i can think of is that the timer reset may be account wide and/or area wide.
Area wide i mean with is, if u open one treasure in say Kourna to soon the timers on the other treasures in Kourna are also reset.

@OP, perhaps u opened a treasure to soon with another character.

The timer is not acc wide, as my bro who plays with same acc but different char was able to open the Istan treasures while I weren't.