Negative Time Management and Overtime

Dear Expert,

In our system we have done positive time mgmt for most of the employees and doing negative time mgmt for few employees.Last month system automatically given 4 hrs of overtime to one employee who is not at all punching because he is coming in negative time mgmt.So I'm surprising how the system is doing this type of calculation.Please help and give ur valuable suggestion.

Thanks & Regards,

Sujata