Incorrect validation error?

The attached file shows an error when "-" (minus sign character) is used 
in an /href /URL.
But in the "Syntax of URL", it appears to be a valid character in a URL.
I tried substituting |'%2D',|but that too was flagged as an error.
As I am a newbie to HTML, PHP etc., I assume I am going wrong somewhere 
- but where?
with thanks,
Alan Bray

-- 
 mob:  0439 630 449
 email:  alan@windsongs.net
 web site: www.windsongs.net