Audio Problem

Hello i am having some problem with play specific audio sources, For some reason i cannot get them to play, I have tried a number of different things but just can't crack it,

     public AudioSource tankEngine;
     public AudioSource tankTracks;
     public AudioSource tankIdle;
 
 
          void Start(){
         AudioSource[] audios = GetComponents<AudioSource>();
         tankEngine = audios[0];
         tankTracks = audios[1];
         tankIdle = audios[2];            
         
     }
 
         void OnGUI(){
         if(CurrentSpeed > 0)
                   tankEngine.pitch = 0.5f + (CurrentSpeed / maxSpeed);
               tankEngine.Play();
 
     }

Everything else works like a charm but except it will not play, If i remove "tankEngine.Play();" from the script then just enable Play On Awake on the GO Prefab's AudioSource then it will work fine with the pitch acceleration etc.

I have been trying to get it to play from script so i can then stop the audio once stationary to play a idle audio clip. Any ideas? Thanks.

Edit 1: I am also starting to get a strange buzzing sound when audio is played Google dosn't help, I am using the correct audio formats, In-fact i have tried every format of audio just to make sure