Pasted URLs with don't seem to work in the web system if they have ampersands ("&") in them. This is caused by the visual page editor, which takes each "&" and transforms it into "&" when the page is saved, breaking the link.
- Click the Edit tab for the page.
- Click the "Edit without visual editor" link below the body text window.
- Scan the links in the source code for any instances of "&" and then reduce those to just "&".
- Save the page.
The link should now work.