L-39 Albatros pilot reported ineffective braking and steering after touchdown; resulting in a runway excursion.

Narrative

This aircraft steers on the ground using differential braking that is activated once the 'weight on wheel' switch on nose wheel is activated.I chose to land on runway XX which is clear of rising terrain on both ends and 12;500 feet in length and 200 feet wide. Tower was closed; and no traffic observed on the ground or in the air; nor responded to my traffic advisory request. I touched down in the first 500 feet and decided to see if the aircraft would stop within the remaining 12000 feet of runway without application if brakes.With almost a 30kt headwind vector and very light touchdown it was difficult to recognize that the aircraft was on the ground until after power was pulled to idle. This also meant that the weight on wheel switch was not activated because the nose did not pitch down; which I did not notice in the dark environment. Typically the aircraft steering is controlled with the rudder down through about 35kts at which time differential braking takes over. It was at this point that I realized that I did not have braking authority and reverted to the emergency system that applies brake pressure equally to both wheel. I allowed the wind from the West to location X turn the aircraft toward an area that was paved; but off runway XX by more than 2OOft between taxiway 1 and 2 just before reaching 3. I left all my exterior lighting on and shut down since I had no steering control to taxi beyond this point.Once I exited the aircraft; I confirmed that the weight on wheel switch had indeed not activated due the soft landing and rollout. I chocked the aircraft and walked toward the ramp where I was met by security and fire rescue personnel. Unable to taxi the aircraft and without proper tug/towbar it was decided to leave the aircraft which was well clear of both runways and wait for daylight and proper tow equipment.The aircraft was properly able to be towed several hours later(approx XA:30pm) to the ramp.No damage to runway; runway lighting; aircraft; nor the sole occupant resulted.The following morning; mechanic specialist consult and taxi test confirmed that the sole cause of brake ineffectiveness was the pilot; the equipment worked proper and correctly. In the future; my first action after touchdown will be to lower the nose to confirm brake authority by positive elevator forward stick pressure to activate this switch even if I then choose to allow the aircraft to rollout without braking.