I received zero points if the opponent in real time ladder have very low points, but lossing points winning seems a bit unfair. :(
WarLight points are never lost (or loosened, or lossed). Once you receive points, they're yours forever.
However, you may be referring to your real-time ladder rating, which can go down when losing games on the real-time ladder.
One thing that's important to realize is that fractional rating points are stored by the system, even if the ratings only show it rounded to the nearest integer. This means while your displayed rating may not have increased after a win, it still likely went up by a fraction of a rating point.