I'm having trouble setting up my first webshop.
I've taken the following steps:

• Installed Umbraco 7.7.7
• Switched language to dutch, and removed english language
• Installed Merchello 2.6.0 (zip downloaded from here)
• Changed metric, language and currency settings
• Installed FastTrack 2.6.0

Then I try to open the store, and it gives me

The given key was not present in the dictionary.

It can't find the "Image" property on the model in the _ProductBox

@if (Model.HasValue("image"))

So, I'm looking at the products. All extended-content-fields are empty. The image-field was a "Label" instead of an "Media Picker".

After changing the PropertyEditor, and selecting all images with the products, I can open the page.

But what is going on here? Is there an error in the FastTrack installer, not installing the correct content? And why can't Umbraco find the property "Image"? Is this a thing from Merchello/FastTrack or does the ModelBuilder ignore empty properties in models?

Edit: re-saving all example products fixed this problem. Still unclear why it happend though.