Why is this transacation taking so long to confirm?

[aqrulesms]

https://blockchain.info/tx/b1630a7faf60e8c93471497ee1b27f5939e24f1c7ee33ca9bc5e0d9ae7a5c5d9

I just noticed I posted this in the wrong section, but it's been a few blocks since the transaction yet it is still unconfirmed.

What causes this to happen, since normally most transactions are confirmed as soon as the next block is solved.

In that sense, what makes a transaction eligible for inclusion in a block?

[1715701090]

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[1715701090]

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[1715701090]

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[Stephen Gornick]

I just noticed I posted this in the wrong section,

You can move it to the Technical Support board yourself.  The link for you to do that is in the bottom left.  The Technical Support board is:
- http://bitcointalk.org/index.php?board=4.0

but it's been a few blocks since the transaction yet it is still unconfirmed.

By the time I looked, Blockchain.info reported 17 confirmations.

There was a fee paid and the total inputs was more than a trivial amount so it normally wouldn't be a transaction that would be delayed, but the problem likely was that it was spending a recently confirmed coin.  In other words, funds that were received were being re-spent without aging.  That is allowed, but may need a slightly higher fee to be included right away in the next block.