Forms Data Controls :: Firing Postback From Repeater Row Click?

I have a repeater which contains a hidden link button that fires when I click a row in my repeater.

Here is the markup for my repeater:

<div id="divResults" style="height: 290px; overflow-y: auto;">
<asp:Label ID="lblNote" runat="server" Text="Note: select a row to edit."></asp:Label> [code]...

Here is the javascript thats added to each row in the rptLocations_ItemDataBound:

Row.Attributes.Add("onclick",
"javascript:__doPostBack('ctl00$mainContent$rptLocations$ctl0" + (e.Item.ItemIndex + 1).ToString() +
"$lbtn_SelectRow','')");

When I click the repeater row it fires the SetLocationControls method. As you can see my repeater is wrapped in a DIV of height 290px. When the are more than 9 rows in my repeater you have to scroll the div down to view this row. When I click this row it does the postback but doesn't fire the SetLocationControls method. I've had a look in the source it's created the click event to the repeater row like all the other rows. why this method isn't firing on the rows that aren't initially visible in my DIV?