Forms Data Controls :: Setting The Selected Index In A Datalist?

I have a datalist that holds imagebuttons which all link to images stored in a database. When I click on any of the image buttons the datalist enlarges the chosen picture and manages to dothis as the datalist is binded by the uniqueID of the image in the database. So, when I am looking at the enlarged picture, it would be nice to be able to click 'Next' & 'Prev' link buttons to move onto the next or previous picture without having to return to the datalist in between looking at a different photo.

I have managed to set up methods for clicking on 'next' and 'prev' linkbuttons that will successfully browse back and forth between photos in the datalist but the selected index always starts at 0, i.e the first photo in the datalist. So if I'm viewing the 5th image in the list and press 'next', the first image in the list shows up. I thought just by clicking on an image button would automatically set the selected index but obviously this is not the case. I have read various threads and tutorials on the net and a lot of them point to dlIcons.SelectedIndex = e.Item.ItemIndex; I have tried to put this in the itemDataBound method for my datalist but it changes nothing. And if i try to put that line of code in other messages in the class i get error messages (I'm using Visual Web Developer C#).

its part of a final year project due in 3 weeks and by now I should be writing the report! The code I'm using is pretty huge and spread out between classes but I will include what I think might help illustrate how it all works:

<asp:DataList ID="dlIcons" runat="server" DataKeyField="AttachmentID"
OnItemDataBound="dlIcons_ItemDataBound" ItemStyle-BorderWidth="1px"
RepeatColumns="5" RepeatDirection="Horizontal" CssClass="Icons"
OnSelectedIndexChanged="dlIcons_SelectedIndexChanged">
<AlternatingItemStyle CssClass="AlternatingRowStyle" />
<ItemStyle CssClass="RowStyle" BorderWidth="1px" />
<HeaderStyle CssClass="HeadeBrStyle" />
<FooterStyle CssClass="FooterStyle" />
<SelectedItemStyle CssClass="SelectedRowStyle" />
<ItemTemplate>
<asp:Label ID="lblFilename" runat="server" Font-Size="Small"
Text='<%# Eval("Filename") %>' ></asp:Label>
<br />
<asp:LinkButton runat="server" id="btnDelete" CommandArgument="<%# Bind('AttachmentID') %>"
CommandName="DELETE" Text="Delete" OnClick="btnDelete_Click"
Font-Size="small" CssClass="btnDelete" />
<br />
<asp:ImageButton runat="server" ID="imgBtnFileType" width="120" Height="120"
ImageAlign="right" ImageUrl='<%#"http://localhost:49279/PDFViewer/GetAttachment.ashx?AttachmentID=" &#43; Eval("AttachmentId")&nbsp; %>'
OnClick="imgBtnFileType_Click" BorderWidth="1PX" CssClass="imgBtnFileType"
CommandName="VIEW" CommandArgument="<%# Bind('AttachmentID') %>"/>
<br /><br />
</ItemTemplate>
</asp:DataList>
The CS file:
protected void dlIcons_ItemDataBound(object sender, DataListItemEventArgs e)
{
if ((e.Item.ItemType == ListItemType.Item) || (e.Item.ItemType == ListItemType.AlternatingItem))
{
DataRowView drv = e.Item.DataItem as DataRowView;
dlIcons.SelectedIndex = e.Item.ItemIndex;
int attachmentID = (int)drv["AttachmentID"];
string fileType = (string)drv["Type"];
ImageButton imgBtnFileType = e.Item.FindControl("imgBtnFileType") as ImageButton;
string fileName = (string)drv["FileName"];
Label lblFilename = e.Item.FindControl("lblFilename") as Label;
lblFilename.Text = fileName.Length > 12 ? fileName.Substring(0, 10) + ".." : fileName;
}
}
The next and prev link buttons onclick leads to these two methods:
public int nextPic()
{
dlIcons.Items.Equals(dlIcons.SelectedIndex++);
int nextAttach = (int)dlIcons.SelectedValue;
return nextAttach;
}
public int prevPic()
{
dlIcons.Items.Equals(dlIcons.SelectedIndex--);
int prevAttach = (int)dlIcons.SelectedValue;
return prevAttach;
}

these were void methods but i've been stuck on this for hours and have resorted to fiddling with just about everything.