Shader Properties gone everytime i put specular/Roughness map to Standart Shaders

![alt text][1] Hi, just straight to my question. i don't know why my shader properties just gone everytime i put something to specular map. interestingly, I can copy old material file that already has the specular map assigned, there is no problem appear if i do this steps. the problem only occur to a new material created. here is the error warnings ![alt text][2] can anybody help? is this bug? im currently using Unity 2017.4.17 [1]: /storage/temp/130609-before-and-after.png [2]: /storage/temp/130610-error.jpg