confussed about CSS expressions

[yawnmoth]

I'm trying to play around with CSS expressions and am having some
difficulty.

<a href="#"
style="b:expression(eval(alert(&quot;test&quot));background:blue">test</a>
....works, as does...

<a href="#"
style="b:expression(eval('alert(&quot;test&quot'))">test</a>

However,

<a href="#"
style="b:expression(eval('alert(&quot;test&quot'));background:blue">test</a>
....doesnt work.

Any ideas as to why?