Detecting which UI button was pressed within canvas?

Hi!

I have like 10 buttons on my UI and I gotta check which one was touched. I was using the following logic and it was working fine, but now I am getting this error for some reason:

 NullReferenceException: Object reference not set to an instance of an object
 DetectButton.Start () (at Assets/Scripts/DetectButton.cs:14)

Any ideas what could be going on? Here is my code (attached to the canvas), and I am using Unity version 5.1.0f3. If you need any other info I will gladly provide, thanks in advance

 void Start()
 {
     this.GetComponent<Button>().onClick.AddListener(() => 
           
                                                     { 

         if (this.name == "btnJogadores2")
         {
             print ("2 jogadores");
             jogadores = 2;
         }
         //QuantidadeJogadores(this.name);
         //QuantidadePartidas(this.name);
     }); 
 }