Re: DS won't "stand"!!
My ds wouldn't do it till waaaay past 8 months. He could do it, but he rarely did. He was on the later (but normal) side for milestones...sat at 9 months, crawled at 14 months and walked at 18 months. He was and still is a 'sitter' who would rather sit in the sandbox than run maniacally like most other boys. He is a thinker not a mover. He is (and was) completely normal in every respect just took him longer to really get mastery over gross motor.
Just don't let stories of 10 month old walkers make you forget that everything has a range, and walking for one has an AVERAGE age of 15 months...which means it falls on both sides.
I guess what you want to do is distinguish between not being able to do it and just not wanting to. My ds just didn't WANT to.