Hello 
I need to be able to manually enter the overtime in other input.

Therefore I created a new other input type called OT Hours (Code: OT_HOURS)

 I created a new Salary Rule named Overtime Pay (Code: OT_Pay).
Category Gross.

Python Condition:
result = inputs.OT_HOURS.amount > 0 if 'OT_HOURS' in inputs else False

And the Code:
overtime_rate = 1.5  

ot_hours = inputs.OT_HOURS.amount if 'OT_HOURS' in inputs else 0

hourly_rate = contract.wage / 160 

result = ot_hours * hourly_rate * overtime_rate

When I try to compute the sheet in a payslip, after manually adding OT in other Input, I will get a Error stating: 
- Salary rule: Overtime Pay (OT_PAY)
 - Error: : "0" while evaluating "result = inputs.OT_HOURS.amount > 0 if 'OT_HOURS' in inputs else False"

Can anybody help me? Do you see an obvious error why it doesn't work?