Change Server Side Use To HTML Image Tag Only

I am trying to wire some fancy Javascript (PopBox) to an ImageButton control and I am getting a very strange run-time (Compilation) error.

<asp:imagebutton id="imgBtnPicture" runat="server"
class="PopBoxImageSmall"
pbshowcaption="true"
title="Click to magnify/shrink"
onclick="Pop(this,50,'PopBoxImageLarge');"
width="90%">
</asp:imagebutton>

I've looked at replacing the ImageButton web control with a simpler HTML img tag (which is what the PopBox documentation suggests). Yet, I don't know how to populate an <img> tag from the CodeBehind file. Here is a typical statement which sets the .SRC property from an ASP.Net dataset row:

Me.imgBtnPicture.Src = theRow.Item("ImageURL")

I've tried this as an alternative:

<img alt="" src=""
id="imgPicture" runat="server"class="PopBoxImageSmall" title="Click to magnify/shrink"
onclick="Pop(this,50,'PopBoxImageLarge');" width="90%"
/>

Visual Studio 2008 does not complain about this declaration above but in the codebehind file, how would I address this so I could populate the .Src attribute.

Intellisense, cannot even "see" this
Me.imgPicture.src = theUrl 'this won't compile...

I added this at the top of the codebehind but seemed to have no effect:

Imports System.Web.UI.HtmlControls