Links automatically inserting own Blog address

Hi there,

I’m trying to insert a link on a picture in my blog, and although the link seems to be correct when I click on the “edit picture” button, when I actually try out the link it goes to a 404 error, as my own blog address has somehow inserted itself at the beginning of the link. It’s as if the linking system can’t understand I would want to link to somewhere outside of my own blog.

Example is that I want the link to be
http://www.ticketsource.co.uk/event/23276

but it seems to constantly convert it to
http://rossiterbooks.co.uk/wordpress/www.ticketsource.co.uk/event/23276

Sorry if this is a really basic question but I’m tearing my hair out here! Any help would be greatly appreciated!