Handling commands in a datalist

Hi everyone, I'm having a problem handling command events from a datalist, more specifically when the command is processed I'm not getting any input the user may have entered.

I have a datalist which is showing some information about an image and providing controls to edit the caption or delete the image:

<asp:DataList runat="server" id="additionalphotos" RepeatDirection="Vertical" RepeatColumns="1" HorizontalAlign="Center" OnItemDataBound="AdditionalPhotos_ItemDataBound" OnItemCommand="AdditionalPhotos_ItemCommand">
<itemtemplate>
  <table align="left" cellpadding="0" cellspacing="0" border="0">
    <tr>
      <td class="formfield"><asp:Label runat="server" id="additionalcaption" EnableViewState="false" /></td>
    </tr>
    <tr>
      <td class="formfield"><asp:Image runat="server" id="showadditional" EnableViewState="false" /></td>
    </tr>
    <tr>
      <label for="addphoto"><td class="formheader5">Image Location</td></label>
    </tr>
    <tr>
      <td class="formfield"><input accept="image/jpeg" type="file" id="additionalphoto" runat="server" class="len5" EnableViewState="false"></td>
    </tr>
    <tr>
      <td class="formheader5">Image Caption</td>
    </tr>
    <tr>
      <td class="formfield"><asp:TextBox runat="server" id="editadditionalcaption" TextMode="SingleLine" MaxLength="50" class="len5" /></td>
    </tr>
    <tr>
      <td class="formfield"><asp:CheckBox runat="server" id="deladditional" Text="Delete this image" EnableViewState="false"/></td>
    </tr>
    <tr>
      <td class="formfield"><asp:LinkButton runat="server" id="editadditional" Text="Submit" CommandName="EditAdditional"/></td>
    </tr>
    <tr>
      <td class="formfield"><br></td>
    </tr>
  </table>
</itemtemplate>
</asp:Datalist>

In the ItemDataBound event I set up the imageURL and the caption label (there is some processing done that's why I don't just use in-place server code to set them).

My first hurdle was getting a button to fire the ItemCommand event, I had been trying with a regular Button but apparently you have to use a LinkButton, not sure why this is the case but I can live with it for now.  Once I switched to using a LinkButton the ItemCommand event was firing and being handled correctly.

Here's my ItemCommand handler:

sub AdditionalPhotos_ItemCommand(sender As Object, e As System.Web.UI.WebControls.DataListCommandEventArgs)
      dim id as String
      id = GetEncVal("id")

      dim strSQL as String

      dim cbDelete as CheckBox
      cbDelete = e.Item.FindControl("deladditional")
      if (not cbDelete is nothing) then
            TRACE.Write("DEBUG", "Found checkbox:" & cbDelete.ClientID)
            if cbDelete.checked then
                  TRACE.Write("DEBUG", "Deleting image '" & e.Item.DataItem("caption") & "'")
                  // CODE TO DELETE IMAGE
            end if
      end if
            
      dim txtCaption as TextBox
      txtCaption = e.Item.FindControl("editadditionalcaption")
      if ( not txtCaption is nothing) then
            TRACE.Write("DEBUG", "Found caption: " & txtCaption.Text)
      end if
end sub

When looking at the TRACE output, the delete checkbox and caption textbox are found, but the checkbox is never considered checked and the caption is always seen as being empty.  Can anyone tell me why this is the case?  Does the command event not count as a submit for some reason?