HTML textfield question regarding <img src="" />

This doesn’t seem to be working:

var url:String = "img/someImage.jpg";
txt.htmlText = "Some text <img src='url' />"

returns an error:

Error #2044: Unhandled IOErrorEvent:. text=Error #2035: URL Not Found. 

Is it possible to use variables as url pointers with img src tag?

Thanks!