The problem is you didn't set slideWidth. In order to setup a carousal, you have to provide 3 values, namely : slideWidth, minSlides, maxSlides.
Here's a working fiddle http://jsfiddle.net/hwQ6C/
$('.bxslider').bxSlider({
slideWidth: 200,
minSlides: 4,
maxSlides: 5,
slideMargin: 10
});