I guess that is too much of styles for simple overlay effect, if you are interested to see a demo I've made from scratch than here you go
HTML
<div class="wrap">
<img src="http://images.google.com/intl/en_ALL/images/logos/images_logo_lg.gif" />
<div class="overlay">Hello This Is So Simple</div>
</div>
CSS
.wrap {
position: relative;
display: inline-block;
}
.overlay {
opacity: 0;
background: rgba(0,0,0,.8);
position: absolute;
width: 100%;
height: 100%;
top: 0;
left: 0;
transition: opacity 1s;
color: #fff;
text-align: center;
}
.wrap:hover .overlay {
opacity: 1;
}