The address is correct, and found on this page :
http://www.pinekan.com/yoyaku.html
If you wrote in English, and no one speaking that language is under their hands, not getting an answer is not so surprising...
If you can write in Japanese, it would probably help the process...
This is really a problem in Iriomote, as the number of foreign visitors is really low, and people not used to deal with them.