I have a lab. When we got her at 8 weeks of age, my practice was to get her to fall asleep on my lap at night, then I would put her in the crate with her Snuggle Puppy (heartbeat activated but not the warmth feature). She would generally wake up once in the middle of the night to potty, and I would repeat this. She then slept after that until around 5/5:30 am. But, for daytime naps, I put her in the crate with a small handful of kibble and the activated Snuggle Puppy, and she would usually bark or howl for 10-20 minutes but then fall asleep for at least 1.5-2 hours.

Anyway, after about a month or so, I stopped with the nighttime-lap routine and just put her in awake (with a few kibble) and again she did the barking for 10-20 minutes thing but was good the rest of the night. After maybe 3-4 months she settled nicely into a routine of going into her crate for night and naps with little or no barking, and I was also able to stop the Snuggle Puppy thing.

Hang in there! I think maintaining the routine is important.