Thanks for your question and for the link to your sample page; very helpful.
I went to the example page, opened the “uitslagen” document list and clicked on an entry. I got the error message you described. I right-clicked on the same link and selected “Save target as” and was able to download the document without error.
I examined the HTML source code of the entry:
<a href="http://bzpc-bodegraven.nl/wp-content/uploads/2017/05/2017-02-19Leiden-Speedo_Jaargangwedstrijden_2017_dag_2_uitslagen.pdf" rel="prettyPhoto[pp_gal]">2017-02-19=Leiden-Speedo_Jaargangwedstrijden_2017_dag_2_uitslagen</a>
Notice the rel="prettyPhoto[pp_gal] attribute and the “Image cannot be loaded poertion of the message. It looks like you have a lightbox plugin that intercepts the click and tries to load the document for display in a lightbox. It’s not an image, so the attempt fails.
You will have to find a way to disable the lightbox function for this gallery, which will be specific to whatever plugin or theme function you are using. I do not believe MLA is directly involved, but here are two recent support topics along the same lines:
Disable MLA lightbox
needless step between image thumbnail and lightbox on portfolio pages
I am marking this topic resolved because I do not believe MLA is directly involved. If you need more specific help on finding and disabling the lightbox function for your [mla_gallery] output, post an update here with more information and I will give you whatever help I can. Thanks for your interest in the plugin.
