Retailers are busy, so do the work for them. Offer a plan of action that clearly benefits their business. Be a good guest. Abide by their rules. Don't badmouth anything they do or put the retailer on the defensive.
Relationships take time.
If you're not getting much response, thank them for their consideration and try again another day. Meanwhile they're looking around and see only 20 titles. But there are thousands of software titles for Macintosh. So when I explained this to Kelly, she went out and found several hundred titles and displayed them on an entire wall in the Apple store. It was very impressive.