I am using a standard code to achieve the same effect over a div. Usually, the following would work:

<Style>
.MouseOver
{
   background-color: #eeeeee;
}

.MouseOverOut
{
   background-color: #none;
}
</Style>

<div style="background-color: #ffffff; width: 222px; height: 198px; padding: 16px; border: 1px solid #CCCCCC;"
 onMouseOver="this.className='MouseOver';this.style.cursor='pointer'" onMouseOut="this.className='MouseOverOut'"></div>

However, on a div, the only way I can make this work if to remove the background-color: #ffffff on the div tag.

For some kind of reason, the mouse over effect does not work if a definition already exists. Can someone explain that?