Template System in list category posts not working

I am trying to get the recent post of different categories being desplaid on my starting page. The short code works. But I need different displays so I want to use the template system of the plugin but I can not get this to work. I followed the available instructions to have the list-category-posts folder in my themes folder and have placed the modified default.php template with a new name into this folder. The short code in the page is limited to the catid and the template parameter. What ever I do, nothing changes. It is allways like the Template has no effect at all.
Can some please help me?
Ps.: I made all the changes on my local test environment, therefor I can’t provide a link to this site.