4.) He's too old. Unfortunately, they don't yet make a Viagra for bettas, and he may just be too old to care about spawning anymore. The best age to breed bettas is between 3 and 10 months; after that there is usually a decrease in virility.
http://www.bettysplendens.com/articl...articleid=1240
Be sure that the seller gives you the age of the betta (typically 3.5-4 months)
http://badmanstropicalfish.com/articles/article44.html
If you buy yours from a large chain store you are often buying a fish that is already between 6 months to a year old.
http://www.nippyfish.net/agingbettas.html