Latest News Thumbnail image

Anyway, I also reinstalled the module before while made some test, and the module looks a bit different with the version before I re-installed it. Did you made some css changes for the module before?

Yes I made some changements in the text style.

to make your modification is update-safe( is not overrided when installing a new update in the future) I'd suggest you to store your css modification on the template css.
Anyway, I've made some tests on my localhost and the thumbnail works properly. Please see this video www.dropbox.com/s/q4dms3job1n5aid/latesttn.mp4?raw=1
But when I tried to turn on the intro text on your website it returns some error message when displaying thumbnails.
Can you check whether this folder exist and writeble :
www.boeimeerbreda.nl/coast/images/latestnewsplus/imagecache/

hmm strange. the module should create the folder ../images/latestnewsplus/imagecache/ if it doesn't exist.
Can you check whether the folder images is writable?
Also, you might want to create the folder images/latestnewsplus/imagecache/ manually and make sure the folder is writable.