Sitemap Generator Forum

after i submit my website's URL  [ External links are visible to forum administrators only ], i wait for quite a long time,and got prompt as follows:
 
An error occured
There was an error while the URL specified: [ External links are visible to forum administrators only ]
Please make sure to specify the correct website URL and resubmit your request.

Can anybody tell me why?what's wrong with my code? how should i modify the code?

Hello,

the error means that your host is currently unreachable on the way from our server for some reason (possibly the connection to your host will be restored after a while).