css-selector doesn't work in FF

Hi,

I have a scripted test that times out with FF, but works with IE.
FF: http://www.webpagetest.org/result/130801_10_1Q97/
IE8: http://www.webpagetest.org/result/130801_YC_1REH/

It uses the following css-selector:

execAndWait	document.querySelector('#san_searchResult section div:first-child a').click();

The set cookies can’t be the cause. Other tests use same cookies and doesn’t fail on FF.

With wptdriver version 96 it worked. I updated to the actual version 126 and now it doesn’t work anymore :frowning:

Regards, Nils