If nothing is coming out of the bottle, it could be because it’s creating a vacuum. This is usually caused by a blocked valve at the bottom of the bottle. Make sure to open the valve properly before each use.
It could also be that the hole in the bottle teat isn’t fully open, as the silicone might still be a bit sticky due to it being new. Try turning the teat inside out and squeezing or rubbing the opening a few times to ensure the hole is fully open. You can also test the teat by holding it under water to see if anything comes out.
If this doesn’t solve the problem, check if you might need a different size teat, depending on the thickness of the feed or your baby’s age.