Custom dimension not working

I’m trying to track custom dimension. The plugin is installed correctly but when I click in the menu it shows only “Value not defined”.
this is the code

var _paq = _paq || [];

(function() {
var u="//";
_paq.push([‘setTrackerUrl’, u+‘piwik.php’]);
_paq.push([‘setSiteId’, ‘1’]);
_paq.push([‘setCustomDimension’, customDimensionId = 5, customDimensionValue = ‘prova’]);
_paq.push([‘setCustomDimension’, customDimensionId = 1, customDimensionValue = ‘bo’]);

var d=document, g=d.createElement('script'), s=d.getElementsByTagName('script')[0];
g.type='text/javascript'; g.async=true; g.defer=true; g.src=u+'piwik.js'; s.parentNode.insertBefore(g,s);



You have installed the plugin, correct?