I checked our site using
http://www.keyworddensity.com and was surprised to see that keywords mentioned in meta-descriptions and meta-keywords are not detected.
Here is how meta-keywords tag looks like at our site : <meta http-equiv="keywords" content="aaa,bbb,...">.
I noticed that most sites use <meta name="keywords" content="">.
Can that be a reason why keywords in our meta-tags do not detected?