Links on home page won't open in IE - html

Question

I haven't found a solution yet..
my links on pictures on my homepage and the link in the ul li nav bar don't work. My links work on other pages except on the home page...
Links to the home-page from the home-page do work.
I only have this problem in IE and IEE. works fine on all other browsers.
Is something standing in the way of IE opening these links? The fault is not in my browser setting. IE finds the links when i hover over them but it doesn't do anything when I click on the links.
This is the code for the not working links:
This is the button image, 1 of the 3
<div class="buttonlinks">
<div class="thumbnail">
<img src="images/Knop1Layer.PNG" class="button">
<div class="tekstblok">
<ul class="buttontekst">
<li>HEALTH ECONOMIC MODELS</li>
<li>BUDGET IMPACT</li>
<li>Art. 81 TOOLS</li>
<li>VALUE TOOLS</li>
<li>…</li>
</ul>
</div>
</div>
CSS:
.button {
width: 200px;
min-height: 80px;
margin: 0 auto;
text-transform: uppercase;
font-weight: bold;
letter-spacing: 2px;
color: #000;
transition: all 0.3s linear;
justify-content: center;
display: inline-block;
line-height: 30px;
}
.button:hover{
opacity: 0.5;
background-color: #FEFEFE;
cursor: pointer;
}
This is the ul li link.
<header class="header"> <a href="home.html" style="text-decoration:none !important;">
<div class="logoheader"><img src="images/hebias-logo.jpg" alt="Hebias" class="logo"></div>
</a>
<nav class="navigate">
<ul>
<p> Tel. [phone]   info#hebias.be</p> <!---link outlook--->
</ul>
<ul>
<li> <a class="link" href="maactivities.html" style="text-decoration:none !important;">Links</a></li>
</ul>
</nav>
</header>
CSS:
a{
color: #7F7F7F;
font-size: 14px;
letter-spacing: 2px;
font-weight: bold;
transition: all 0.3s linear;
cursor: pointer;
text-decoration: none;
}
a:hover {
color: #FFF;
}