Gulp error on ionic setup sass



please can you help me with this ?

Thanks a lot (I am newbie)

$ ionic setup sass
npmnpm WARN package.json snowboard@1.0.0 No README data
npm WARN prefer global ionic@1.6.4 should be installed with -g

Successful npm install
Updated /home/louisro/Documents/mobileApps/BoardLine/webapp_et_new_PGBuildversion/www/index.html <link href> references to sass compiled css

Ionic project ready to use Sass!
 * Customize the app using scss/
 * Run ionic serve to start a local dev server and watch/compile Sass to CSS

[19:44:40] Using gulpfile ~/Documents/mobileApps/BoardLine/webapp_et_new_PGBuildversion/gulpfile.js
[19:44:40] Starting 'sass'...

      throw er; // Unhandled stream error in pipe.
Error: source string:468: error: error reading values after (

Error running gulp sass

Exception with  (CLI v1.6.4)

Your system information:

Cordova CLI: 5.3.1
Gulp version:  CLI version 3.9.0
Gulp local:   Local version 3.9.0
Ionic Version: 1.0.0-beta.13
Ionic CLI Version: 1.6.4
Ionic App Lib Version: 0.3.8
OS: Distributor ID:    Ubuntu Description:    Ubuntu 14.04.3 LTS 
Node Version: v0.12.7