I am building a new layout. I layed out the Fastrack, set up a central hub and tested it with two different engines. I used three 4' X 8' sheets of soundproofing board. No problem. Everything ran well. Constant speed and no dead spots anywhere. Then I screwed down the track--not every piece only enough to keep all the track stationary throughout the entire layout. Now I have 5 - 6 "dead spots" that stop the engines cold. I did not solder the individual track pieces together and I used what I see as two different kinds of Fastrack---one with silver rails and one with blacken rails. I believe the Fastrack with black rails is an older version of that product. What did I do wrong?