It looks like you are using an ad blocker. That's okay. Who doesn't? But without advertising revenue, we can't keep making this site awesome. Click the link below for instructions on disabling adblock.
Sometimes it just gets a bit wedged in a crooked spot, just wiggle it a bit and it should release. If not, you can get a replacement buckle for like $20, but mine get wedged all the time and it makes it get stuck that's all.