All land rovers are permanent four wheel drive so not certain what you mean when you state you are putting the car into four wheel drive. The smaller gearlever(diff lock) should do two things 1 enable to select high and low ratio with a neutral position in between
2 the other function is engagement of the diff lock. When engaged a light comes on the dash. It appears that you have the second gear lever in neutral hence no drive.
Normal driving on road you should have the diff lock disengaged and be in high ratio.
Suggest you read up in the handbook
maurice
December 2009