You just hired a new employee. You're excited about the future, to see the value that this person will bring to your team.

Then, just weeks or months later, it becomes clear things just aren't working out. And you have to begin the tortuous process of firing them. That means going back to the drawing board and beginning the long process of screening candidates all over again. Aside from this being frustrating, it's extremely costly. Millennial turnover costs the U.S. economy nearly $31 billion annually.

So what's going on? Is the media right about Millennials? Are they fundamentally flawed? Or, then again, could it be you and the way you hire and train new employees?

As a workplace author, speaker, and consultant, I've had countless consultations about hiring, onboarding, and firing employees with business owners and hiring managers. The scenario above is more common than you'd think--and the reason you hear from the managers is equally ubiquitous: Blame the Millennials for being too greedy, lazy, entitled, you name it.

What I advise my clients to do is to put aside the finger pointing and instead take a much deeper look at why their new hires aren't panning out. What they end up finding is a powerful opportunity to spark change within their organizations. Here are three common mistakes that managers find they make when hiring and training new employees.

Not digging deeper into overly polished interview answers

"But they nailed the interview!" I've heard this refrain from countless hiring managers when they're doing an autopsy on an employee relationship gone south.

But the reality is, most interviewers only focus on what the interviewee says--which is just a small part of the puzzle. What's more telling is what candidates don't say or avoid talking about during interviews. I learned this during my decade as a broadcast journalist, interviewing hundreds of people for top television networks. Don't treat interviewing like an afterthought--it requires research, study, and practice.

For example, before the interview, conduct online research on a candidate. You may find something key, like prior work experience that doesn't appear on their résumé. Why is this? What kind of online presence does this person have? Do their social-media posts conflict with your company values? When you look them up on LinkedIn, do you find that their last two jobs lasted less than nine months? Why?

It's your job as an interviewer to do research, connect the dots, and bring up these kinds of questions during an interview (within the confines of the law, of course). Have a philosophy: What kind of person is the right hire for your business?

Not looking beyond the references a person provides

Over the years, I've been surprised to learn that only a small percentage of hiring managers actually reach out to a potential hire's references. This is akin to purchasing a home without ever conducting an inspection.

Always call a candidate's provided references, of course. But I challenge hiring managers to go further. Odds are that a potential employee isn't going to provide you with references who are going to say bad things about them. Thanks to LinkedIn and other social-media sites, it's easy enough to find peripheral references and connections--potentially even in your network--to learn more about a candidate. This could be through contacts you have with the candidate's former employers, college alumni networks, professional organizations, and even college professors for young professionals just starting out.

Not setting clear expectations (or setting unrealistic ones)

Check out the job description for the last job you posted. Now be honest with yourself. Is it accurate? Like, really accurate? Are you portraying your company for what it actually is or what you'd like it to be? Is the job description really what the employee will be doing, or is it glamorized and misleading? If it's the latter, it could partly explain why only 29 percent of Millennials are engaged by their work.

During the job interview, did you set clear expectations for what the employee should expect in terms of company culture, future raises and titles, metrics for success, and how you work? Even if the interviewee doesn't ask about these things, it's your responsibility to share this information. Because less than 30 percent of Millennial employees believe their current organization fully utilizes their skills and experience--an outcome that's mutually wasteful.

So next time you find yourself asking if that employee just isn't a "good fit," stop and ask yourself: Did you do your job in the screening, interviewing, and hiring process? And what can you do now to engage an employee, turning him or her from a potential fire into a valuable hire?