That's not how you use the negative lookahead. It won't work. For example, 

'<a href="..." target="...">' =~ /
   <a            # Matches '<a'.
   .+?           # Matches ' '.
   (?!target)    # Matches. (/\Gtarget/ doesn't match.)
   .+?           # Matches 'href="..." target="..."'.
   >             # Matches '>'.
/isx;

[download]
and 
'<a target="..." href="...">' =~ /
   <a            # Matches '<a'.
   .+?           # Matches ' t'.
   (?!target)    # Matches. (/\Gtarget/ doesn't match.)
   .+?           # Matches 'arget="..." href="..."'.
   >             # Matches '>'.
/isx;

[download]

The common use of a negative lookahead is 

/(?:(?!$re).)*/

[download]

See my earlier post for the fix.

In reply to Re^2: Regexp: Match anything except a certain word by ikegami
in thread Regexp: Match anything except a certain word by fraktalisman

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