For Christmas this year I was given an Overland Express Limited train kit.  I went to set it up this morning after weeks of preparing my room for it.  I have installed a perfectly flat surface for this kit.  After getting the train connected on the track it derails almost immediately.  9 out of 10 times it will derail the minute it hits the section of track with the power connected to it. I have tried this with the cars attached to the engine,  just the engine.  There is also no common factor One time it will be the front wheels  the next it will be the back wheels.   Also the cars will not stay coupled together.  Any help or ideas you might have to this issue would be greatly appreciated.