Sitemap Generator not generating

[Bryony]

Hello,

We've just launched a new website [ External links are visible to forum administrators only ] but I cannot get xml-sitemaps to generate a sitemap.

Here is the error message that I am receiving:
There was an error while accessing the URL specified: <b>[ External links are visible to forum administrators only ]</b>
Please make sure to specify the correct website URL and resubmit your request.

I haven't come across this problem in the past, so any help would be much appreciated!

Thanks in advance and all help welcome!

[XML-Sitemaps Support]

Hello,

although your website homepage opens in browser, your server returns 404 http header with it, which means "not found" result. Please check here:
https://www.xml-sitemaps.com/http-headers-viewer.html?op=http-headers-viewer&go=1&pageurl=http%3A%2F%2Fwww.egypttravelplan.co.uk%2F&se=xmlsitemaps&submit=View

[SLB]

Hello,

I am also trying to create a sitemap for: www.iwt.co.uk 

The message 'There was an error while accessing the URL specified' appears even though I can access the website. 

Do you know what the problem could be?

Thanks.