Fire animation not tile

What I expected to happen was...:
Fire Animation should dock. The first and last texture of fire in fire_0.png and fire_1.png should coincide with a difference of 1 pixel.

What actually happened was...:
Fire animation not tile and animation looks abrupt.

Steps to Reproduce:
1. Make fire.
2. Take a close look at the fire.
3. Fire animation looks abrupt.