Well, I think you should check if your selector is in your webpage like that :
casper.then(function(){
console.log(this.getPageContent());
});
command -pipe the output-: casperjs test yourFile.js > seePageContent.html
Or you might prefer this way (with a wait if needed) :
casper.then(function(){
this.wait(3000,function(){
var fs = require('fs');
fs.write("seePageContent.html", this.getPageContent(), 'w');
});
});
That way you know if your element is present or not. If not, then your previous step is wrong.