If you cannot redeem your Steam Wallet voucher code after purchasing it, please check that the store country/region of your Steam account matches the currency value of the Steam Wallet card you purchased.
For example: if you are using an account in Taiwan, then you must ensure that the store/country of your Steam account is Taiwan, and use Taiwan dollars as your transaction currency, and your Steam Wallet steam card must also be in Taiwan dollars.
*If you want to check your account region, you can click "View My Account Details";
*If you wish to change your Steam account region:
- Open the Account Information and Edit Settings page.
- On the right side of the form, select "Update Store Country" and you will be able to update the store country and wallet currency.
For any concerns related to the store region of your Steam account, please refer to: https://help.steampowered.com/en/faqs/view/2B3F-DAEF-846B-A0E8
Or contact Steam customer service directly: https://help.steampowered.com/zh-tw/wizard/Login