Bash script is killed even with nohup

I have a webserver written in node.js and I have a bash script that starts it:

nohup `node ~/path/to/app.js -ms` > /dev/null 2>&1 &

stderr is redirected to stdout and both are redirected to /dev/null, I don't want any output file.

The process is executed in background and is executed with nohup.

The problem is that I access to the server via ssh. If I logout the process is still executing but a few hours later the process dies. What I'm doing wrong?

EDIT:

Forget nohup and &. Specific node.js solution:

boot.js

require ("child_process").spawn ("node", process.argv.slice (2), {
    stdio: "inherit", detached: true
}).unref ();

Usage:

node boot app.js <params>