For what html code standard are you using the validator to validate? What is the name of the HTML validator are you using?
Also a little more of the code is gonna be needed as a reference as to where the error occurred within the code and the tags already around it... If I'm not making any sense its ok its pretty late.. I just need more of the html code to see what possible errors in syntax there is.
And lastly what program are you using to write the code in the first place?