tape player doesnt take tape correctly?

when i put in a tape it acts like it takes it then switches back to radio, then a few seconds later switches back to player, never starts playing tho, and only way to stop it from switching back and forth is to turn the car off. hope this is understandable, not sure how to word it, hopefully this has happened to someone else, and have asked. this is on a 1999 ford escort zx2.