Try this one
protected void rad1_CheckedChanged(object sender, EventArgs e)
{
if (rad1.Checked == true)
{
rad2.Checked = false;
}
}
protected void rad2_CheckedChanged(object sender, EventArgs e)
{
if (rad2.Checked == true)
{
rad1.Checked = false;
}
}
protected void rad3_CheckedChanged(object sender, EventArgs e)
{
if (rad3.Checked == true)
{
rad4.Checked = false;
}
}
protected void rad4_CheckedChanged(object sender, EventArgs e)
{
if (rad4.Checked == true)
{
rad3.Checked = false;
}
}
hope It will be helpfull for You.
Thanks