Verizon fails to purchase the files from cart

Hi there,
I want to purchase a song and this error appears and tells me that is not available anymore. On the cart is available and I don’t know why is not working. Can anyone help me please to fix this ? how should I proceed next ?
Thanks !

Sorry
The following item(s) could not be purchased:
RingbackTone “Whistling in the dark”
We’re sorry. These are no longer available and should be removed from your cart.
{Item Name} Code: 247
