Why do I get different results between Browser lab and IE 9 Dev tools

[Vincej1657]

HI - I'm using an Nth Child selector. This is not supported in IE8 so I have a conditional style sheet for IE8. When I test my pafe using the document mode set to '8' in IE9 the browser sees my conditional style sheet and renders properly. However, whenI use browser lab do test my page with IE8 it ignores my connditional style sheet and the result is a mess.

What should I trust more ? Is this a known issue with Browser lab ?

Many Many Thanks  !

[Ben M]

Document mode is different than running IE8.  If you want a more accurate representation I usually recommend the IE Tester http://www.my-debugbar.com/wiki/IETester/HomePage .