Iframe In Update Panel is Not Working

I have repeater control and iframe in same update panel.

In repeater control, Link buttons are placed. On Click event of that link button, I want to update my Iframe. I am updating Iframe By javascript code.

But The code is not working.

 

Here is the designer Code:

 

 

And Code Behind Is:

 

protected void LinkButton1_Click(object sender, EventArgs e)
{


FilterResult();
Button button = (Button)sender;
string buttonId = button.Text;
DataTable dt_OwnerFilter = new DataTable();


dt_OwnerFilter = bl.BL_FetchOwnerInfo(bo);


lblfetchdata.Text = string.Empty;
int i = 0;
foreach (DataRow dRow in dt_OwnerFilter.Rows)
{
butId = dt_OwnerFilter.Rows[i][0].ToString();
if (buttonId == butId)
{
if (dt_OwnerFilter.Rows.Count > 0)
{
string htmlcode = "";
htmlcode = " " + i + "";

ClientScript.RegisterStartupScript(GetType(), "Javascript", "javascript:fnShow(" + dRow["PropertyDetailsId"] + "); ", true);

break;
}

}
else
{
i = i + 1;
}
}
if (dt_OwnerFilter.Rows.Count == 0)
{
lblfetch.Text = " Zero Results Found For Your Search...!!!.";
}

}