Why can't I buy a WoW Token?

I'm having trouble purchasing a WoW Token. Could you please explain why I might be encountering this issue? I've made sure I have enough gold in my account, but the option to buy the Token is still not available. Is there a specific requirement or restriction that I'm missing? Additionally, are there any known issues or maintenance currently taking place that could be affecting my ability to make the purchase? I would appreciate any insight you can provide to help me resolve this matter.