protoc command error

[Do-U-Believe-In-Fate]

when I use the cmd "protoc" with arg "--govalidators_out", it reports an error as following:
protoc-gen-govalidators: program not found or is not executable
Please specify a program using absolute path or make sure the program is available in your PATH system variable
--govalidators_out: protoc-gen-govalidators: Plugin failed with status code 1.

the import path is green, meaning that ...validator.proto is imported correctly, so i don't know where is the problem