As everyone else has already said, your image doesn't exist. If you use the Chrome inspector you can see that the following image doesn't exist.
http://www.mafiaomerta.com/images/userbarsempty.png
It looks to me like you've got two of the same class .bar_a in your CSS and I'd suggest combining them together and choosing one of the backgrounds.
Also the whole of your statistics box is floated, so you'll need to float your bars as well. Delete any reference to .bar_a in your CSS and replace it with the following:
.bar_a {
background-image: url('/bar_a.png');
width: 150px;
height: 12px;
border: 0px solid #3e3e3e;
float: left;
}
Read up about floats to get a better understanding:
http://www.w3schools.com/css/css_float.asp
By doing this you should achieve the following result