Radio Button focus Issue

See more:

ASP.NET

I have written below code in radio button list check change event

protected void rblStatus_SelectedIndexChanged(object sender, EventArgs e)
    {
        //To get focus on radio button which is selected
        var script = string.Format("document.getElementById('{0}_{1}').focus();", rblStatus.ClientID, rblStatus.SelectedIndex);

        if (ScriptManager.GetCurrent(this) != null && ScriptManager.GetCurrent(this).IsInAsyncPostBack)
        {
            ScriptManager.RegisterStartupScript(rblStatus, typeof(RadioButtonList), Guid.NewGuid().ToString(), script, true);
        }
        else
        {
            ClientScript.RegisterStartupScript(typeof(RadioButtonList), Guid.NewGuid().ToString(), script, true);
        }

        //	Open - 1
        //  Close - 2
        //	Extension - 3
        //  Completion - 4	
        //	Inprogress - 5
        
        List<CorrectiveActionExtension> correctiveActionStatus = new List<CorrectiveActionExtension>();
        correctiveActionStatus = (List<CorrectiveActionExtension>)ViewState["dataSource"];

        int i = 0;
        foreach (CorrectiveActionExtension CAItem in correctiveActionStatus)
        {

            if (i == int.Parse(ViewState["index"].ToString()))
            {
                txtDescription.Text = CAItem.Remarks.ToString();

                if (rblStatus.SelectedValue.Equals("3"))
                {
                    divTargetDate.Visible = true;
                    ulTargetDate.DateTime = (CAItem.TargetDate == null ? DateTime.Now : CAItem.TargetDate);
                }
                else
                {
                    divTargetDate.Visible = false;
                    ulTargetDate.DateTime = null;
                   // txtDescription.T
                }

            }
            i++;
        }
        mdlChangeStatus.Show();
    }

In which code used to get focus on radio buttonlist is

var script = string.Format("document.getElementById('{0}_{1}').focus();", rblStatus.ClientID, rblStatus.SelectedIndex);

        if (ScriptManager.GetCurrent(this) != null && ScriptManager.GetCurrent(this).IsInAsyncPostBack)
        {
            ScriptManager.RegisterStartupScript(rblStatus, typeof(RadioButtonList), Guid.NewGuid().ToString(), script, true);
        }
        else
        {
            ClientScript.RegisterStartupScript(typeof(RadioButtonList), Guid.NewGuid().ToString(), script, true);
        }

Now my issue is while loading this i dont get focus on selected radio button from radio button list.
Please help me to solve this.