Specular reflection problem with day/night simulation

Hello! I've got stuck with one problem. Im using unity3d 5, and recently i've created simply day/night system, that rotates sun, and changes some parameters such as: RenderSettings.ambientLight and RenderSettings.reflectionIntensity. So RenderSettings.ambientLight prefectly updates with every change i've made, but when i change RenderSettings.reflectionIntensity parameter via script like this:

RenderSettings.reflectionIntensity = ReflectionIntensity;

Inspector variable changes, but Standart (specular setup) material don't updates. Basicly what i want - set reflection intensity at day to maximum, and at night - to minimum. Most intresting thing is: when day passed and night has come (inside my project) and RenderSettings.reflectionIntensity updated ( to 0, for example), and i manualy drag slider with RenderSettings.reflectionIntensity - it updates.

Am attaching screenshots:

Hope that somebody can help me with this problem, thanks for reading this!