Trying to add a method to initiate a glacier restore, getting an incorrect signature

Code here: https://github.com/3ft9/goamz/blob/master/s3/s3.go#L609

When I use this method I get this exception: "The request signature we calculated does not match the signature you provided. Check your key and signing method." Other methods work perfectly so I'm pretty sure it's something I'm doing wrong. Anyone got any pointers?
