I killed my CATTLEYA WARSCEWICZII .......

[zxyqu]

Just from the sound of it, I'd imagine it was a root problem. Might have occurred when you switched media, as I'd imagine the bark holds more moisture than the LECA. I am guessing a bit though. Were you doing S/H, or just using LECA as the media? Either way it sounds like tha plant wasn't getting enough water, so the leaves shriveled (did they also get really weak/limp?), and didn't have enough energy to put into the new growth.