I am having the same problem with my king, he is active and has shed a few times just not eating, and I think BrianS had the same problem with his kingsnake too, mine has eaten about 3 times in 5 months, It gets quite frustrating.
Is your king losing weight? mine hasn't yet, i'm hoping he will start to eat again now, he shed yesterday and had a bowel movement, which I thought odd as he hasnt ate for a while.
If he hasnt lost any weight from when you got him I wouldnt start to worry yet, try warming up the mouse, although it didnt make a difference to my king, he snubs it no matter what, all you can do is keep offering for the time being, I wouldn't try live if he's been eating f/t. just give him a little more time.
I have a difficult rat snake that will not eat unless he is in the smallest rubbermaid and the rubbermaid all wrapped up and dark, and left alone, if I put him in a bigger one, he just wants to escape all the time and ignores the mouse, I have others that wont feed with the lid on, I have different snakes with different eating habbits, try to find one your king is comfy with, I am going to try the small tub with my king.
If your king has ate on a couple of occasions he will be ok, snakes can go a long time without eating, mine has gone since November on just 3 or 4 mice.
keep us posted
