"Could not find `npm` command. Is npm installed?" when starting nide

Install nide use "npm install -g nide" successfully. After that, type "nide init" to start nide and initialize a new project, there is error message: "Could not find npm command. Is npm installed?"

I installed the nide using npm, and I'm sure that the npm is in the PATH. How can it ask me "Is npm installed" ?