Well sometimes you win some and sometimes you lose some. This time it was an epic FAIL!

Here's what I tried:
Two venison shanks - seared on each side.
Removed from pan, added 1 onion, 2 celery stalks, rosemary sprig, bay leave, 2c red wine, 4c beef broth, 2 cloves garlic and simmered until onions were translucent. Added shanks and simmered for another 5 minutes.
Added the whole mix to a roasting pan, covered with tin foil and put in a 250 degree oven for 1 hour.
After 1 hour I took it out, turned the shanks over and returned to the oven for another hour.
According to the recipe 2 hours should have done it. After 2 hours my shanks were as tough as shoe leather! So I thought it may need another hour to 'break down'. Another hour in the oven and it was no different. The whole thing went in the trash.
So the family had a vegetarian night (ugh).

Has anyone braised shanks with any success? Tips, tricks, or different recipe?