Addressing Employee Absenteeism
The only sensible thing you should do is speak to him and understand the reason. Realize that you are an organization and you are an HR person, not a military dictator who shall be sending people to the gallows if they fail to march along the thin line of discipline your management has drawn on the ground.
I get a creepy feeling that your organization needs some competent people within its senior management and the HR department as well. Also, as a premonition, you may soon hear from one of the Employee Associations or Unions to explain your policies and procedures, specifically your disciplinary procedures.
P.S.: Labor commissioners are tightening their rules in dealing with employee grievances, so you may want to be a little careful in being too stringent with discipline.