FLStudio doesn't play certain instruments, in my case it happened for FPC and Drumpad (on different projects). They show a red name for the WAV file's name (which obviously means it is not there.
However, when I press ...
FL can't find the path for the sample? I have 4 locations set for my FL search folders. Downloads, Main Image-Line Folder, all of my iTunes music, and my own folder where all of my releases are organized ...