Why wont this beer carb???(2nd batch)

Last year I tried brewing a beer that had agave nectar as ingredient. To date, about 110-130 days conditioning, only 2 beers carbed up. I just thought it was an anomaly. So recently I tried the same recipe again to see if i could get better results. Ive brewed about 20 different batches of all kinds of styles and all of them showed very apparent signs of carbing as early as 5 days. I usually dont throw a few in the fridge until after 30 days of carbing, just to see how theyre doing. Its been 20 days now since bottling this second batch of agave beer. At least this go around it is showing minute signs of carbing, but nothing close to what it should be after 20 days conditioning. My question is this: is the agave the culprit for the long period of carbing/no carbing? Is it possibly affecting the yeast and killing it? All of my batches condition at oraround 68-71 degrees. Is that a bit too cool perhaps? I know, time and patience is the key. But for the same recipe to have the same poor results is frustrating. I even recapped several of the first batch about 90 days ago and still not a single sign of carbing up. The recipe was a pilsen extract with a couple of pounds of agave. I boiled the pilsen for about 45 minutes, then added the hops and agave for the last 15 or so. At bottling time i added 5oz of priming sugar and bottled.

If the agave was killing the yeast, you wouldn't have had fermentation. How was your FG?

It sounds like something else to me, but I've never tried agave in a recipe so I have no experience to add.

this may be a dumb question but does the agave have a preservative in it?

I have primed with agave nectar before to great results

The first batch had a lot of agave in it, 4lbs to be exact. The OG was 1.067 @ 75deg. The FG was 1.033. The second batch I toned down the agave to about 2 lbs. The OG was 1.057 @ 81 and the FG was 1.007 @ 68.

I got the agave at Trader joes. Its supposed to be 100% organic, no preservatives.

Perhaps the caps aren't sealing?

I just chilled and opened a different beer that I bottled on the same day as the above beer and after 20 days, its carbed up great! Definitley gonna condition for much longer, but I wanted to see how it was doing. I believe I used Wyeast 1007 for the agave beer.

Daffypuck said:

I got the agave at Trader joes. Its supposed to be 100% organic, no preservatives.

Click to expand...

Organic Preservatives?

This just doesnt make since. The odds of the same 2 batches not carbing because of a capping problem or bad yeaast or whatever are fairly large. Brewing isnt rocket science, well at least extract brewing isnt. I really want this beer to turn out so i can make it for the spring and summer season. Any other ideas on what might be causing this?