Stuck on neckband!

My pattern says the following. …
pick up and knit 34 stitches along left side of neck, pick up and knit 34 stitches on right side of neck and 16 stitches from 17 cast off stitches at back of neck. 85 stitches.
where on earth are those 17 coming from? What am I casting off? I don’t end up with 85 stitches if I include 17?

Welcome to KH. You should have bound off stitches on the back neck.

What pattern are you doing? A link to it if possible is helpful.

Do you mean that I pick up 33 stitches on back of neck, then cast off the first 17 stitches of the neck? It doesn’t make sense to me!

When you finished knitting the back of the sweater, did you bind off sts? That’s where the pattern wants you to pick up the 16 sts to complete the circle for the neckband. (True, this won’t add up to 85 sts.)
Do you have sts on a holder at the back of the neck rather than bound off sts?
Can you give us a link to the pattern or a pattern name?