I ever face that problem and my solution :
Find these lines (in httpd.conf) :
#LoadModule rewrite_module modules/mod_rewrite.so
remove # sign
and this line
<Directory />
Options FollowSymLinks
AllowOverride None
Order deny,allow
Deny from all
</Directory>
change into this :
<Directory />
Options FollowSymLinks
AllowOverride FileInfo Options
Order deny,allow
Deny from all
</Directory>
Save and Restart apache followed by retest your permalink.
( I take it from my blog post that utilize xampp but I think it’s not different in wamp).