Turnouts

I have a problem with a left hand turn out. When I throw the switch for the train to turn on the side track, the engine continues straight and the wheels come off of the track. I’ve cleaned the frog area and use a dental tool to remove any bits of ballast and closely inspected the area. I can not see anything that could cause the problem. Any ideas on how to correct this?

What brand of turnout? If it’s an Atlas, the point rail may be too low to catch the wheel flanges, or the rails may be out of gauge. This seems to be a common problem with Atlas turnouts.