Download Link not worknig

Download link not working when I used Hide/Mask Real Link option
my website hosted on 1and1 hosting
how can I fix that? I guess that problem in cURL but when I click on link Check if cURL is enabled. return cURL is enabled.

I used last version WordPress, Email Before Download, and Download Monitor.

Thanks!

http://wordpress.org/extend/plugins/email-before-download/