EZ Track #6 Crossover Derailments

[don1884]

I just recently purchased a #6 EZ track Crossover and I am having a strange problem. First of all let me say that I have a number of turnouts ( 6 ) with no problem. With the Crossover track every car after the engine derails when going straight through the crossover. When the switch is set to the right track the train goes through with no problem. I have checked the couplings on the cars and they are not catching any track. If I take the train through the crossover at approx. 10 m.p.h. it will usually make it through. Anything faster and the cars derail. No problem with the engine. The engine makes it through at any speed. I'm a newbie with only a couple of months of experience.  I'm having a great time with my Grandson and the train set. We will be going to the Greenberg Train Show in Wilmington MA. this Sat. Any suggestions will be greatly appreciated. I have a little over 100' feet of track and running one train on DC. Thank You. My next question will be about changing plastic wheels to metal wheels. Is it worth the trouble?