Last five bottles flat?

I had twenty five perfectly carbonated, beautifully bubbly and clear lager.

Went to share one of my last five bottles with a friend and it was flat. Opened another and that was flat too.

Fortunately I had some other home brew (draught) to share so we had that and it was fine.

I checked the remaining three bottles of lager this morning and they are all soft to squeeze (plastic bottles).

The beer is a Coopers Lager from a can. In primary for two weeks. In bottles for 27 days. Primed with two Coopers priming tabs per bottle (750ml).

The bottles are brand new and never used before... as are the caps.

When I examined the bottles this morning I noticed two of the three caps have separated from the ring thingy that gets left behind when you unscrew a new cap... if that makes sense. The other one is fine. But the bottle is still soft.

Any help? I just have no idea what happened. It's like it was perfectly carbonated then went flat.

Edit: It is summer here so the bottle conditioning was done at very warm temps.

... possiable you forgot the tabs on those 5 bottles??? i dont mean anything by this, but i started useing a bottleing bucket and piriming the entire batch at once because i was unfortunate enough not to remember to put tabs in every bottle (had 8 bottles of a 52 bottle batch not prime with priming tabs).. somtimes 5 gallon batch nets 50-54 bottles and thats alot of variables to forget... or its possiable you had caps which didnt have the little 02 blue plastic thingy and did get an O2 seal.... alot of things could go wrong.

Cheers

It was my first batch and I was pretty careful to put tabs in every bottle. Plus it would be a heck of a coincidence for the five without tabs to be the last ones I drank and all in a row.

The bottles are brand new from the Coopers Brewing kit so they should have been fine.

Are you saying you don't like it when something goes soft before it was supposed to?

I am not familiar with these Cooper's bottles. It sounds different from what I am used to seeing . . . unless they are the same type caps as you would find on two liter bottles of soda? If that is the case and the bottom ring is separated than it sounds like maybe the pressure in the bottles popped the seal just enough to release the pressure and, alas, go soft prematurely. With no consideration towards you at all. The cads.

lol thanks for that... maybe that is the cause - too much pressure... at least I'll know for next time I share a beer to make sure the bottle is firm to squeeze...

It was a little embarrassing...