Clicking a cube to load scene

ok i have a cube with a script to make it float in water and i want to make it so when i click on the cube with a right click it loads a new scene no matter what i do it wont work ive looked at all other threads related to this and read through the script reference but it still wont work this is what i put onto the cube function OnMouseDown() { if (Input.GetButtonDown ("Fire2")) { Application.LoadLevel("GameScene"); } }