Skin morph problem

I create 3 morph,  morph 0, morph 1, morph 2, after adjust influence angle. i
found morph 0 percent down from 100 immediately but morph 1 percent wait for a
few frame before it start from 0. it make vertices go  the wrong way.  this not
happen between morph 1 and morph 2, it down and up  immediately. i try to adjust
falloff graph but it not help, how to fix this.