Action For Late Coming Even After Deduction

Dear All,
Very Good Morning...!!
In our company, we do deduction for late coming employees. But one employee, who never bothers about his deduction. He continuously is coming late without any intimation.
Even I issued Memo, no change found. He is playing vital role in his department.
Please let me know which action can be taken against him..

What Plant Head/ MD/Owner has to say over this? Because at the end of the day this position can guide you better...
Why he is late? What can be done to reduce/avoid his late comings?

1. If you wish to inculcate discipline, stop deduction and start taking disciplinary actions properly.
2. If an employee is habitual offender, put it on record by taking necessary action.
3. Good performance does not give liberty to be undisciplined. He may be playing a very crucial role, find another person to play that role. No employee, irrespective of his/her position, performance, qualification, contacts, importance, is not important enough to spoil the atmosphere of complete company. such people are expandable.
4. You need to play your role cautiously, diplomatically and very intelligently to move ahead.