Question

Button 

<asp:Button ID="btnAdd" runat="server" Text="Add"/>

Label 

<asp:Label ID="label1" runat="server"></asp:Label>

Set button visible when the label1.text is different from “”

Answer 1

I dont see you the label will get text during runtime unless it happens with jquery. So i will go with this approach:

Firstly add a style attribute to the label like so:

<asp:Label ID="label1" runat="server" style="display:none;"></asp:Label>

And then when the page loads do the following:

$(document).ready(function () 
{ 
  if ($("#label1").text() == "")
  { 
    $("#btnAdd").show();
  }
});

The question is very unclear though.