Hello! I'm sorry to hear about the issue you're facing with the 100% free shipping voucher on Shopee. There could be a few reasons why you're encountering this problem:
1. Voucher Restrictions: Some vouchers have restrictions on the products or categories they can be used for. Make sure that the items in your cart are eligible for the 100% free shipping voucher you're trying to use.
2. Minimum Spend Requirement: Check if there's a minimum spend requirement for the voucher to be applicable. If your total amount doesn't meet the minimum spend, the voucher may not be usable.
3. Voucher Expiry: Ensure that the voucher you're trying to use hasn't expired. Expired vouchers won't be accepted at checkout.
4. Account-Specific Voucher: Some vouchers are account-specific and can only be used by the intended recipient. Make sure that the voucher you claimed is supposed to be used on your account.
If none of these reasons seem to apply to your situation, I recommend reaching out to Shopee's customer service for further assistance. They should be able to investigate the issue further and provide you with a resolution.