[Yeast] Staining for spores

[FDavis]

Hi, I saw the post on schaeffer fulton staining and was curious if  
anyone had an answer.  We just did a lab in which the entire class  
was unable to get the endospores to stain.  Apparently this is a  
chronic problem with this lab.  We were wondering if it might have  
something to do with low humidity and/or high altitude?  Any ideas  
would be helpful.  I don't know which form of malachite green was used.

Thanks,
Francesca Davis