Does the tag 'vertical-align' actually work in CSS?

I’m trying to get some text to align to the middle of a 30px high div on my site, and I got the tag vertical-align: middle; from the W3Schools site, but it doesn’t seem to work… the rest of the CSS style is:

.tabl {
background-image: url(‘images/tab_l.png’);
background-repeat: no-repeat;
float: left;
color: #FFFFFF;
text-align: center;
min-width: 9px;
min-height: 30px;
max-width: 9px;
max-height: 30px;
}