There will be three things to look for while testing the system.
Once the interface board is online go to the programs menu and select 'Interface Settings > Test Sensors'. Making sure that none of the Photocells are blocked, all lanes should be GREEN. If not, you will have to retrace your wiring and assembly. Using a solid object, break the light beam and the lane color should become RED. Do this for ALL lanes. Also click on the 'Lane Indicator' buttons and the corresponding Lane Indicator LED should light. Now try activating the Start switch. The status color should change from green to red (allow the timers to 'time-out' before continuing - the Red status light will light when finished). If all is working properly you are ready for the next step. If not you will have to re-check all your wiring. Remember to check for fused (melted insulation) wires from the result of the heat gun.
If you see all of the above, congratulations, you have successfully built and installed your Grand Prix Tracker project! If not, you will need to retrace your steps and I am confident you will find your problem(s).