As I said, no one is perfect. An invalid size in the previous version of this set may have been the cause of an error in the download. I have recreated the .ico files and uploaded them to the set. The download now functions properly.
The triple flower icons are too weighty and create a similar problem so I am moving them to another set and reducing the available sizes to alleviate this problem.
Find the new triple Dahlias set here: http://www.rw-designer.com/icon-set/dahlias
Sorry for any inconvenience this has caused.