I am going to guess, and say that you are using 000WebHost. The problem there is that, even though they have cURL enabled, it does not work the way it should. You will need to find another host that has it enabled. I suggest
Free-Web-Host, even though it adds its own javascript code. (If anyone knows how to turn it off, please tell me.) It has fully working cURL, and works beautifully. I have tried every single one of the inviter scripts in this forum, and other sites, and they all work. I do suggest
dwild's automatic invite script. It is my favorite, and works the best.
~iZ3RO