Once we feel like neither is happening, we want to move on. At my best, I'm a star worker. Anyone I've ever worked with or for will attest to that. At my worst, I'm the crankiest, most ungrateful malcontent you could ever have working for you. Not to say that you haven't hired a bunch of slack-asses in the past.
Some people just have bad luck that way.
Figure out how you can get your employees involved in your company in a personal way. Better yet - get them involved in figuring that out. Find people in your company who seem to have a real impact on others, who can lead and who understand what motivates their peers. Give them more responsibility and encourage them to mentor others in the company. Institute an employee referral program - where employees are rewarded for bringing in other employees.