The effectiveness of the physical actuation at each stage will be examined first, such as the precision in the wafer carrier movement, the acceleration in the pick up movement, and the operation of valves in pressurization and vacuuming procedures. If no problem is detected, process parameters can be checked, such as the amount of vacuum and its settling time. Further investigation may lead to the examination of the sequential functional execution of the control software and eventually the sequential logic itself. In this manner, the troubleshooting becomes a logical and systematic procedure, stemming from the AD table and matrix.