title: when click on empty asp:textbox I want to set the visibility of a asp:label to false immediately
body: <p>when click on empty asp:textbox  I want to set the visibility of a asp:label to false immediately
  i set some label's to validation check 
  when the textbox is empty , the label become visible but when text changed or clicked on textbox to edit it is not invisibled
  please help me</p>
  
  <p>code :</p>
  
  <pre><code> protected void Button1_Click(object sender, EventArgs e)
  {
      if (TextBox1.Text == "")
          Label1.Visible = true;
  
  }
  protected void TextBox1_TextChanged(object sender, EventArgs e)
  {
      Label1.Visible = false;
  
  }
  </code></pre>