My wife and I are taking a parenting class at church called "Love and Logic".  One of the key points on the first day of the class focused on how kids learn lessons of life.  They told the story of a young child who spent 6 months of allowance on a cheap plastic toy that broke after only an hour of playtime.  It is a painful lesson for a kid, but not nearly as painful as a college graduate who goes into debt purchasing a car that is hardly practical or affordable.  The point is that a lesson learned in childhood often saves a more expensive mistake later.

Consider about how that might apply to your employees.  Do you give your employees enough opportunities to "mess up"?  I see business leaders "protect" their employees from mistakes all the time by not giving them opportunities to screw up (or excel at their job). 

When I was an engineer at ADM, I was in charge of a process that produced millions of pounds per day of corn starch.  I made several mistakes both on the process and in managing the operators and contractors that worked on the process, but the plant manager continued to be very supportive as long as I learned from my mistakes and worked to avoid them when possible.  One headhunter who called me told me that other companies loved engineers from ADM because they were so well trained.  He commented that ADM excelled at keeping their engineers "just a little over their heads" in work and responsibility. 

Keep your employees challenged and allow them to make mistakes from time to time.  Your investment will really pay off!