If the pins are sharp try running it down the outside wall of your house - against the bricks. This can file the ends off a bit and makes them less sharp
But deffo follow the advice above about working from the ends of the coat up towards the root - don't try from the root out ie one sweep of the slicker/comb, or you will make any knots far worse and create matts
Some dogs have coats that knot more easily than others and similarly some that de-knot easier too. My Jasper's coat is by and large a dream froom that perspective (although it has gone very fluffy and more curly thanks to the coat king). If it does get knotty they usually come out easily whereas Buddy is totally different and he is also a big wuss and hates being brushed too which doesn't help. The key is to use a good conditioner after bathing and spraying diluted conditioner on between baths too. Try using a detangler spray - I know some people find them effective - I don't but I think that's just me. Try and keep the coat really well conditioned and that helps stop knots in the first place but makes them easier to remove too.
I also find that if there are some knots/matts that wont brush out then I bath them and put undiluted conditioner into a washing up/squirty type bottle, and squirt it right into the middle of the knot/matt. Leave it to soak in for a few minutes only lightly rinsing out. Then I leave it to dry and try again - this often helps. The knack is not to work at the knot/matt too much or you just make it worse.
Another trick is to use a matt splitter and break the matt down into several smaller ones that may then tease out with a slicker.
I don't use a comb as I find that makes them worse and pulls more than a slicker - but again - that's prob just me and the way I use the comb
hth
