Until recently the GenDex Network only was able to index a gendex.txt file which was placed in the root. They have changed this policy recently so now it is possible to index the file from a subfolder.
This is not possible because the data folder is a protected folder which can not be reached from outside webtrees. Use better error handling instead f61c83fc65f4229e0dac6282dc9dc2f8d841e718
Until recently the GenDex Network only was able to index a gendex.txt file which was placed in the root. They have changed this policy recently so now it is possible to index the file from a subfolder.
See: http://www.webtrees.net/index.php/en/forum/4-customising/30239-fancy-gendex-module#52728