The simplest way to identify inconsistencies in the logic of your Trading System is to run it on the history data. 
To do this in offline mode you will need to download this data to the Tester at least once. Run  .NET Station, connect to your broker, and open a chart with the instrument you want to test.

Note: The 'Save offline data' setting in  .NET Station has to be enabled to store the history cache and to be able to use it in offline mode in PTL Builder.

Click the button in the Project tab or simply use the F5 key to compile and run your Module in the Tester. You will be able to track execution while your Trading System is running. The Tester will show you open positions and placed orders while executing just like a Chart panel in  .NET Station.

You can pause execution at any time to explore variables or go through step-by-step.

Once testing is finished you will be able to analyze results in the Testing Results panel. They are stored there each time you run your Trading System and you can compare results before and after optimization.

Automatic Optimization

Once your Trading system is tested on the History and you've also defined all settings needed to set up it, then you can perform Automatic Optimization. There is a tool called Optimizer in PTL Builder for this. When you run this tool, the Optimizer will take the settings one by one and run them on the History in different combinations, trying to achieve your target. This target may be the Highest Balance, Lowest Drawdown or some exact P/L relationship, etc.

Run your Trading system in Tester several times with different parameters before start optimization to make sure there is no serious logic errors left.