Alright, I had the unfortunate event of breaking a string on my classical guitar. I went and got more (Augistine strings), but the new ones won't hold like the other ones did. What I mean is that when I tune the guitar, in less than 5 minutes, the strings will drop a half step. I followed exactly how the other strings were put on (the same knots by the bridge and on the actual tuners). So what I am wondering, should I change the knots? what knots should I use? Or is there something I missed while putting them on (perhaps melting the ends so they don't slide)?

Any help would be appreciated.
Some of the most powerful moments are when there is nothing to be said
Since the strings are nylon, they are very fussy, but when tying knots, use the tension of the string to your benefit, buy wrapping it back, around, and under the string going down the neck, so that the tighter the string, the tighter it will hold it.

Its hard to find a knot that works for you but once you do, its easy.
Nylon strings stretch more than their steel counterparts, mine generally take at least 1-2 days to fully stretch out and hold tune, even with prestretching. Make sure that you give it a loop at the slothead on the treble strings too, that can help prevent some slippage.
If you're going to do something wrong, do it
Yeah, I looped it back around and under twice, so that the rest of the string wouldn't slip out, and I found out that also makes the tension tighter, which is good.

I just put them on maybe like 2 days ago, I guess I'll give it a little more time.
Some of the most powerful moments are when there is nothing to be said