I put SPRING5 but left a space and it didnt work, i just ordered the Grizzly Salmon Oil 64 oz using SPRING5 without any spaces in the end or begining and it worked, i just ordered 30 seconds ago. try again, maybe you added a space by mistake, let me know if it works, their number is 877-284-0350 i am sure they will award it to you.
Summer5 is currently working for 5% off. Also, you may try Bark10 for 10% off (it may have just been a weekend promotion).
BTW, I'll add my 2 cents about this website. Unbelievable top notch service. I got a call after my order just to be sure I was satisfied with my experience from them. I get my orders in about 2 days as well, but that's probably because I'm only a state over. They also seem to have the lowest price, at least on what I order.