BJT switch connections
I think you will see the problem yourself if you remember that for an NPN transistor to pass large currents from the collector to the emitter you must cause current to flow into the base terminal. Because there is a PN junction between the base and the emitter, it is therefore necessary to raise the voltage of the base terminal about 0.6V above the voltage of the emitter terminal. Don't make the mistake of thinking that you just need to bring the base to a voltage about 0.6V above ground. That's a common misconception because you usually see the NPN transistor used with its emitter tied to ground.

You can also think of this from the emitter's point of view. If the voltage at the emitter starts to rise for some reason then the transistor will stop conducting current once the emitter voltage rises to about 0.6V below the base voltage. So, the emitter voltage can't ever be higher than the base voltage when the transistor is conducting. Now, think about the voltage you are using to turn the transistor on and off. The emitter voltage must always be lower than that voltage.