Unity plays only a few gameobject's sound

I’m developing a 2D game, and have a Button prefab what plays a sound when clicked.

I have multiple instance of this prefab on my scene, but only 2 of them plays the sound, the others don’t play anything, or just a very short something.

I thought that it is caused by the distance of the camera and the gameObject, but if I place a button what is silent, to the position of a working button, it still won’t play anything.

My code is simple:

public AudioSource myAudioSrc;

public AudioClip btnSound;
protected virtual void OnMouseUpAsButton() {
    if(!isEnabled) { return; }
    myRenderer.sprite       = normalImg;
    transform.localScale    = normalSize;


    //üzenet küldése az objektumnak a message metódus hívására az data paraméterrel
    target.SendMessage(message, data);


I’ve got this working with the code:

AudioSource.PlayClipAtPoint(btnSnd, Camera.main.transform.position);

So it has to do something with the distances.

Is there any better solution?

If you are developing a 2D game, and you think that the problem relies on distances, you can just use 2D sound (if you are using Unity5, open the AudioSource and set Spatial Blend = 2D; or click on the sound asset and uncheck the 3D Sound checkbox).

It turns out I disabled the gameobject with the OnMousUpAsButton event… It’s embarassing