I am not sure what you mean. Page 508 shows a *label*, not an image, like this:
<asp:Label ID=âImageUrlLabelâ runat=âserverâ Text=â<%# Eval(âImageUrlâ) %>â /><br />
A Label has a Text property which, in this case, simly displays the path to the image.
On page 515, the label is then changed to an image to show the actual image:
<asp:Image ID=âImageUrlâ runat=âserverâ ImageUrl=â<%# Eval(âImageUrlâ) %>â />
Where exactly did you see the code you posted here?
P.S. Since this is a server side issue, the browser you're using doesn't matter. asp:Label or asp:Image never makes it to the browser. Instead, these controls are turned into their respective HTML (a span and an img tag) which is then sent to the browser.
Hope this helps,