Labels Not Showing Required Value?

I have a page with a datalist on it, with an image button and some labels in the datalist item(1,2).

I have some more labels on the page which get their values from querystrings(17,18).

I have more labels which are empty (34,35)

On image click in the datalist item, i want the labels from that item to add with the labels outside of the datalist, and the last lot of labels to show this number..

Currently it doesnt do this. Here is my code:

protected void Page_Load(object sender, EventArgs e)
{
Label17.Text = Request["b1"];
Label18.Text = Request["b2"];
}
protected void ImageButton1_Click(object sender, ImageClickEventArgs e)
{
DataListItem item = ((Control)sender).NamingContainer as DataListItem;
Label Label1 = item.FindControl("Label1") as Label;
Label Label2 = item.FindControl("Label2") as Label;
Label34.Text = (int.Parse(Label1.Text) + int.Parse(Label17.Text)).ToString();
Label35.Text = (int.Parse(Label2.Text) + int.Parse(Label18.Text)).ToString();