meteor project : Message : Module is not Installed

In my meteor project, on the server side, in main.js, I have the following code

import { SyncedCron } from 'meteor/percolate:synced-cron';

SyncedCron.add({
  'name': 'Mise a jour GPS',.....

'meteor / percolate: synced-cron' is underlined and the message is "Module is not installed"

Can someone tell me how to correct this error. This is just a warning I think, but I don't like warnings, I'm always afraid that it hides a real error.

Thank you for your help.

YC