There are a few possible reasons:
To buy cryptocurrency on MaiCoin, your account must be activated by completing basic identity verification and bank verification. Please refer to MaiCoin Identity Verification for details.
You can only have one active buy order at a time. You must complete the payment for your previous order before you can place a new one.
If you want to cancel an incomplete or unsuccessful order, please refer to the following instructions: How do I cancel my current order?