Olight T10/T15 question

I bought a 2007 model Olight T15 last year (runs on a single AA) and liked it enough that I bought a brighter 2008 model, but also with the T10 (123A) body tube. I thought it was a pretty good idea-to be able to run the same light off of either AA or 123A batteries-and both lights run just fine off of either body tube/battery combination.
Yesterday I thought I would try one of the lights with both T15 (AA) tubes together, making it a 2xAA light, but in that configuration the light won't come on. Reconfigure to single cell, and it works with either tube/battery.
First I thought it was a contact problem, because the 2xAAs (Eneloops) in the double tube seems to be just a smidge shorter, so I stretched the spring in the tailcap to be sure it made contact, but still no dice. With a single 123A, it's running on 3v, with a single AA, it runs on 1.2-1.5v, with 2xAA, it should run on 2.4-3v, right?
Any ideas?

Is this a dumb question?

Since I discovered this forum, I have bought 2-G2s, 1-9P, 1-E2DL(awesome light!), an M60, M60LF, M60LL, and a 6D drop in from Gene Malkoff, 6-TLE-5EX upgrades for all the AA maglites laying around the house, these 2 Olights, and lots of AA rechargables and 123A primaries-oh and an MH C-9000 to charge them all. This should be proof enough that I WILL follow your advice.

It's not a dumb question at all. I can't think why it won't work, other than one of the AA's isn't charged, or the body parts aren't tightened properly (which I presume you've checked). You could clean the threads on the extension tube too, but I doubt they're so bad it isn't even coming on. I don't have any better ideas, but didn't want you to feel you're being ignored.

This is what i like to do, make sure that you clean the battery contacts with an eraser before you put them on the charger.....i make this a habbit when i put the batts on the charger. Let us know how it goes if the light comes on or not.

Got it! There was no problem with the battery charge or battery contacts, but your replies made me check further.

Couldn't get continuity when both bodies were screwed together. I assumed that the current went through the threads but checking with an ohm meter, found out that it won't (the male side threads are anodized along with the surface of the body). There is a flat bare aluminum end on the male side and inside the female side, but they didn't screw together far enough to make contact with each other. I made a little aluminum foil oring and put it between the bodies to fill the gap and it now works. Thanks! (By the way, there was no contact problem body-head or body-tail because these threaded ends were the correct depth for each other.)

Now my question is what do I gain by using 2xAA instead of 123A, other than a light that is a lot longer? The brightness appears to be the same as with the single 123A, which is definitely brighter than with a single AA (190 vs 120 lumens for the Cree Q5, according to Battery Junction). I assume it will give longer run time? Anyhow, thanks again.

2 AA's will give you longer runtime and easy battery availability as well as a nice rechargable option (ie Eneloops and such).

Output should be similar to CR123.

It will be a lot bigger and heavier than CR123 of course...