Validating a Button's text in C#

 I have a Button that has an initial text as 'Add New", when clicked, i change the button's text to "Save". I wnt to validate this button against the button Text"Save" so that if there is any error behind the function when i initialize save, it gives me an error message.
 
Please can someone show me how to do this in C# using ASP.Net or any other method or way to carry this out?
 
Thanks 
Kingsley
 
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