Multistrike and elemental damage with attacks PROBLEM

Hello everyone,

So my issue is the following, i am playing a custom lightning strike build ( Shadow assasin ) and i did notice that when i replace multistrike with elemental damage with attacks my lightning damage on tootltip jumps from 7400-44500 to 12500-78000. BUT......when i use multistrike and elemental damage together the lightning damage remains 7400-45000.

What am i doing wrong?