Change onclick of an image

I have an html img

<img id="btnViewSpec" alt="View Spec Sheet"src="/images/viewspec.jpg" style="cursor: pointer;" />

I need to alter the onclick to target different aspx pages based on what's read from the database. Something like:

If DBRead("Keywords").ToString.Contains("glove") Then
    Me.btnViewSpec.Attributes.Add("onclick", ("window.open('/SpecSheet/DisplayPDF.aspx?pa=/SpecSheet/GloveSpec.aspx?pid=" & intProductId & "','wnEmailInfo', 'menubar=no,width=820,height=500,toolbar=no,scrollbars=yes,status=yes')"))
Else
    Me.btnViewSpec.Attributes.Add("onclick", ("window.open('/SpecSheet/DisplayPDF.aspx?pa=/SpecSheet/ClothingSpec.aspx?pid=" & intProductId & "','wnEmailInfo', 'menubar=no,width=820,height=500,toolbar=no,scrollbars=yes,status=yes')"))
End If

Problem is I can't get the code behind to recognize the image. I tried to register it in the designer code with Protected WithEvents btnViewSpec As HtmlImage but no luck. I guess I just don't fully understand the issue or w开发者_JAVA技巧hat gets registered in the designer code. Thanks

add runat="server" to the image tag and you will have access to the control