Files don't download

Hi,

So I have loaded up the plugin and have version 2.6.8. I successfully add two files which are downloadable from a page using the shortcode [wpdm_file id=2]. When I add these files to a category and show the tree on a page using [wpdm_file id=2] they display on the page fine but clicking on them just causes the folder to close and nothing downloads.

Where am I going wrong?

Thanks in advance,
Mark