Shouldn't it be <tagclass></tagclass> insteadof <tag-class></tag-class> ?
This error informs that it is looking for tag <tagclass>
Check on the top of the tld file which dtd you are using 1.1 or 1.2. Like you can see below both specifications defines <tag> differently. For me it looks like you took file written for 1.2 and you're trying to validate it using 1.2.
In
http://java.sun.com/j2ee/dtds/web-jsptaglibrary_1_1.dtd <!ELEMENT tag (name, tagclass, teiclass?, bodycontent?, info?, attribute*) >
but in
http://java.sun.com/dtd/web-jsptaglibrary_1_2.dtd <!ELEMENT tag (name, tag-class, tei-class?, body-content?, display-name?,
small-icon?, large-icon?, description?, variable*, attribute*, example?) >
In the future remember to check structure of your files with dtd or XMLSchema if you see such error. Manually or automatically using some tools. It will help You to save some time.
Best Regards
KArol Muszynski