Hi Arv,
I agree with Kunjal. However, I'm not clear though if this person is a new hire or an existing employee of your organization.
New recruits and existing staff will require you to handle the matter differently. Of course, the first thing you should find out is why.
I don't believe you would end up hiring the wrong person for the job unless you don't have a proper recruitment procedure in place (but then again, there is always a slim chance that it will happen).
For a new recruit, it may be due to 'fitting in' difficulties. Then, you may have to look at and assess your orientation again. Perhaps he needs time to adjust to the new work environment or has difficulties doing things the way your organization wants them to be done. Maybe colleagues are not giving him the necessary assistance or guidance, etc.
If it's an existing employee, perhaps it is due to boredom, lack of recognition, poor morale, being disgruntled with work/fellow colleagues/the boss, etc.
What I'm trying to say is there are a lot of possibilities, and you need to find out the "root cause" and deal with it. Otherwise, you will still have this problem.
My humble thoughts.
Regards,
Ricardo