Refreshing an aspx page on Radio Button clicked

I've got an a text box and a button I want to enable /disable upon radio button checked

protected void chkBookActive_CheckChanged(object sender, EventArgs e){

    txtCourseTitle.Text = " no input required"

    txtCourseTitle.Enabled = false;

    btnSearch.Enabled = true;

}

I've got all of this I just need it to take place on page when the button is checked. Nothing happens and I believe the checkChanged event should update automatically? but it doesn't do anything? Super easy to anyone versed in c#/asp.net