1) The first step to unfold the appliance has not been performed correctly.
Make sure you pull the stand slightly up before you release the push button. Also be aware that on a smooth floor the legs of the appliance will automatically move outwards. If the floor is not smooth, for example a carpeted floor, you may have to put your foot on one of the legs to allow the other leg to move outwards.
2) The lamp unit is probably not in the right position.
Make sure you turn the lamp unit in the horizontal position until you hear a click.