API request returns 401

English Transactional
1

I can ensure that my API key is new and copied correctly, but for some reason, it returns 401 Can you tell me how to troubleshoot the problem? I searched online but couldn’t find any effective method.
image

{
    "message": "not verified",
    "code": "unauthorized"
}

nextjs code：

 const headers = new Headers({
        'accept': 'application/json',
        'api-key': apiKey,
        'content-type': 'application/json',
    });

    const body = JSON.stringify({
        sender: {
            name: "demo",
            email: "demo@smtp-brevo.com",
        },
        to: [
            {
                email: recipientEmail,
                name: recipientName,
            },
        ],
        subject,
        htmlContent,
    });

    const response = await fetch('https://api.brevo.com/v3/smtp/email', {
        method: 'POST',
        headers,
        body,
    });