"Add Hours" button under a billing record will become available under the following conditions:
- Task should have a logged hour
- Task should have Revenue set to User Hourly, Role Hourly, User Hourly w/cap, Role hourly w/cap, User Hourly Plus Fixed, Role Hourly Plus Fixed
- If Revenue is set to User Hourly a user for whom an hour is logged should have a billing per hour set under his/her User Settings
- If Revenue is set to Role Hourly the user's primary role should have a billing per hour under Setup
- If no billing per hour set under Setup then billing rates can be set from project's Billing Rate tab.
- Billing Rates on the project override job role billing rates.
- If "Require time to be approved for this project" is checked under Project Settings then project manager approval is required in order for hours to be added to a billing record.