I activated a snipe and changed the snipe to 4 seconds before auction ends but the auction ended at a lower price than my maximum snipe bid.

Did eBay have a new guard or filter against Myibidder?

Please provide the item number in question so I can check it for you.

If you activated your snipe with a few seconds left to go, it may be the issue. Your snipe must be ready at least a few minutes before auction end:
http://www.myibidder.com/login/faq/4/#q5

Here is the item number:
260768110027

I set the snipe a week ago, but set it to "activate" or bid 4 seconds instead of 6 seconds before auction ends.

Unfortunately, there was a short downtime this morning and your snipe was affected by that.
Everything is back to normal since than.
We are working hard to minimize those kinds of issues.

I'm sorry it happened with your snipe. I hope you will find the same or better deal on the same item.