I have a 2 year old bitch who is on day 15ish of her season and she just won't stand for the stud. She has been flirting tail up and to the side for days and yet she won't stand, as soon as he puts a paw near her back she sits down. Anyone got any suggestions as to what is going on as I just don't get it, my other girls have always stood from days 9/10 - 13/14 I have never encountered this.
Thanks for reading.

If you are 100% sure she is receptive then you may have to hold her (not forcibly) so that she doesn't try to move away. She doesn't know what she is supposed to do. How experienced is the stud dog? If he is also a maiden then you may not get a mating at all. He won't know if the time is right. If he is experienced then be guided by him.

I would want to have a Progesterone test result to be sure she is ready as I would not be happy holding a bitch that wasn't ready, but if she is seeming willing and just moving at the critical moment, but not showing any negative objection to the advances then gently holding her with a hand under the tummy may be enough to steady her.

I have a very flirty girl who is not actually ready until at least day 18, and has had her litters from matings on day 18 - 20 and days 19 - 22.  with her first litter we were worried as to why the dog wasn't proceeding to mating as she seemed very willing, so a progesterone test showed that eh was quite right and had no intention of wasting his energy on a bitch that had no yet ovulated.

>She has been flirting tail up and to the side for days

Which can't be taken as totally reliable.  I have one bitch that does this from day 3, but she is a total trollop.  She doesn't sound ready to me.  And the days that other girls stand is no indication.  I have had bitches mated on day 8 up to day 28 at the latest, and puppies from all these matings.  No two bitches are alike, and a lot of bitches vary from season to season, and are not always the same each time.

I use my most experienced boy to let me know when a bitch is ovulating.  I think a progestorone test is probably the way to go for your girl.

As you already have a litter and was so worried about not having a mentor any more, would it not be best to leave this mating for the time being until things are more settled? (I assume it is the same bitch you mentioned had been to stud recently and not a third one.)

my foundation bitch stands from day 22 to 27 have had 2 litters from her, eldest daughter stands day 24 to 29,second daughter stands 20 to 25 days, her granddaughter stand 20 to 25 there is no such thing as a standard time to mate, the owners of the stud for foundations second litter have been the breed since the 60s and have never seen anything like it, their last home bred bitch had been mated three times on day 13 and 15 to proven studs and since having seen our bitch they think they were mating her to early