If your mop is not emitting steam, it may simply require some time to transfer water into the heating component of the mop.
Once the mop has been powered on for 2-3 minutes, it will begin to release the steam.
This delay can occur when the heater is completely depleted after the previous use.
If you leave a small amount of water in the heater, it should produce steam quicker the next time you use the steam mop.