I’ve been learning Houdini for a while,but I have some problem when I was doing the water rending.

Some frames lose the highlight(pic2),and about ten frames later,things get back to normal(pic1). The frame(pic1) just jump to the other one(pic2), without any ramp.

I’ve tried:
1.I checked if there’s any key frames for the materials,none.I delete the old material,and give the liquid surface a new material,still have that problem.
2.Things were the same in the render viewer.
3.I thought maybe the environment light’s problem,I delete it,create a new one,can’t solve the problem.
4.I was wondering that maybe it was because my simulation had something wrong,but the simulation seemed just fine without material.
5.I tried to just render the surface of the water,something more odd happened,the two frames still not the same and they were even more different(pic3,pic4).
I’ve tried anything I can,but I still can’t find or solve the problem.I’m just a rokkie and know little about Houdini.Really looking forward that someone could give something or some possibility.
Thanks for any reply!