sorbias if you put "ObjectName.opacity" - it gets the opacity value currently for the object , putting a number to it will make it not work should be a syntax error judging from your example
you can also use Lerp to do Camera delay to the position of the player too typically making a sprite to act as the camera with the scroll to behaviour and setting the position of the player (usually my camera target)
///Every tick - CameraSprite -> set position
X - Lerp(Camera.x, CameraTarget.x, 0.1)
Y - Lerp(Camera.Y, CameraTarget.Y,0.1)
try this example if you want to understand it, This is what helped me to understand it after seeing it work