Michael Kyba is having trouble mating yeast.
You don't have to play violins, but you ought to try treating them to a
It sounds like you are doing the matings directly on selective medium.
Although this shortcut often works, it's still a shortcut. You're asking
the cells to grow enough in the absence of whatever they need to mate. Try
doing exactly what you're doing but on YEPD plates. Let the shmush grow
4hr-overnight, then replica-plate to selective plates.
Michael lichten at helix.nih.gov