lz.Browser.getLoadURLAsLzURL().host problem w/swf9

[tglines]

The following works when compiled for swf9:

<canvas title="Test" width="99%" height="99%" debug="true"
proxied="false" oninit="Debug.write( 'canvas initialized' )">

<dataset name="execute" request="false"
src="${'http://servername/cgi-bin/somecgi.cgi'}"
type="http" timeout="1800000" />

<view x="50" y="50" width="100" height="100" bgcolor="blue" />
</canvas>


The following, does not:

<canvas title="Test" width="99%" height="99%" debug="true"
proxied="false" oninit="Debug.write( 'canvas initialized' )">

<dataset name="execute" request="false"
src="${'http://' + lz.Browser.getLoadURLAsLzURL().host + '/cgi-bin/somecgi.cgi'}"
type="http" timeout="1800000" />

<view x="50" y="50" width="100" height="100" bgcolor="blue" />
</canvas>


Both work in swf8. What am I doing wrong?