[TYPO3-mvc] Fluid: Object-Accessor is not always working

[Robert Schneider]

I have this Fluid section:

<h1>{product.title}</h1>
<div class="product_picture">
     <f:image src="{imagePath}/{productImage}" alt="{product.title}" />
</div>
<h1>{product.title}</h1>

The first line is not getting resolved. In html I see
<h1>{product.title}</h1>. But the next object accessors work properly. 
It seems to me that f:image initializes something.

How can this be? What is wrong?

Regards,
Robert



PS: The full template is (Show.html):

<f:layout name="Default" />

<f:section name="main">
	<f:render partial="FormErrors" arguments="{object:product}"/>
     <style>
         .circle {
             padding: 40px 100px 110px 100px;
             background: #fff;
             width: 400px;
             height: 450px;
             margin: 10px auto;
             border-radius: 50%;
             -moz-border-radius:50%;
             -webkit-border-radius: 50%;
             behavior: url(ie-css3.htc);
             border: 5px solid orange;
         }
     </style>
	<div class="circle">
         <h1>{product.title}</h1>
         <div class="product_picture">
             <f:image src="{imagePath}/{productImage}" alt="Produktbild 
für {product.title}" />
         </div>
         <h1>{product.title}</h1>
         <div class="product-description">{product.description}</div>
         <div class="product-productCode">{product.productCode}</div>
         <div class="product-price">{product.price}</div>
         <f:link.action controller="ShoppingCart" action="add" 
arguments="{product: product}">Zur Merkliste hinzufügen</f:link.action>
     </div>
</f:section>

and Default.html is just:
<div class="tx-forumproducts">
	<f:render section="main" />
</div>