The margin does not work? Need for space between two elements

First of all, I do apologize I don't put my link here, it's a site for work and I'm not allowed. I'll post the relevant parts of my code if necessary though.

So the problem is pretty basic - i have one div with some images, and a header <h3> below where my content starts . No matter how much I try to create some space between the two, it doesn't work. I've tried margin and padding on both elements, changing between position relative and absolute, and throwing in lots of <br> tags. Nothing works!

What causes my two elements to be so attracted to each other? What may cause inability to create space between two elements?


Edit: here's my css code for the div:

.bmwrapper {
width: 720px;
position: relative;
margin-left: auto;
margin-right: auto;
z-index: 1;

.bmvenstre {
float: left;
text-align: left;
z-index: 1;

.bmhoyre {
float: right;
text-align: left;
z-index: 1;

So it's one big div that acts as a wrapper, and two divs (left and right) inside. The links are displayed as blocks:

a.bmlink {
display: block;
margin: 0;
padding: 4px;
font-family: Tahoma, Verdana, Segoe, sans-serif;
text-transform: uppercase;
font-size: 18px;
font-weight: bold;
letter-spacing: 2px;
color: #08A;
text-decoration: none;
z-index: 2;

The header below this div is just a <h3> tag, then there's some text. Hope this helps!

You can try 2 things:

1) Put the elements overflow:hidden

2) put the elemnts display:block

If number 2 messes up with your design, try putting them float:left;

Since I don't have the code I can't give you more information, but when margins/paddings do not work, it is usually because you are either applying it to an Inline item (hence number 2) or you have a container where everything inside is floating, so the container won't have the proper height (hence number 1)