Aria-expanded on anchor: W3C validator error

I am trying to use aria-expanded on an anchor element but the W3C
validator gives an error. It expects an attribute role.
I do not understand why. I am using the attribute on an allowed element.
Even if I used role=link or role=button, it fails.

<a id="l1" href="javascript:myscript1('l1')" aria-

expanded="false" aria-controls="block1">Review Techniques</a>
I am using <!DOCTYPE html>
I appreciate your Tips / suggestions.
Sailesh Panchang

Received on Monday, 8 July 2013 13:40:18 UTC