errors validating html 4.0

I'm secondary teacher, and I'm making an html 4.0 tutorial. When I try to validate my page the only error is the following:

    there is no attribute "TARGET" for this element (in this HTML version)

Then I've searched at the html 4.0 reference at W3 web site and I find that the use of target is correct.
So, what's the problem?
Thanks. My tutorial's web site is 
    http://www.terra.es/personal3/tutorialhtml/

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Manuel Almonacid
malmonacid@retemail.es
malmonac@openbank.es