SiteMap Error

[innominds]

When I submit the sitemap, I get the error message that

"Network unreachable: robots.txt unreachable
We encountered an error while trying to access your Sitemap. Please ensure your Sitemap follows our guidelines and can be accessed at the location you provided and then resubmit. "

I'm repeatedly getting this error. Why is it so?

[minstrel]

Are you getting this error for a subdomain? Where is the robots.txt file located and where is the sitemap file(s) located in relation to the URL? If it's a subdomain, they need to be resident in the root of the subdomain rather than the root of the main domain.

[innominds]

It is for the main domain itself.
Even for the wordpress plugin the message is same.

[wige]

What is the domain of the site, and the location of the robots.txt and sitemap file?