尝试使用HTTP请求连接到TestRail时出现身份验证错误

Question

我试图在VBA for Excel中建立与TestRail API的连接，但我一直收到此错误

"{"error":"Authentication failed: invalid or missing user\/password or session cookie."}"

这是HTTP请求

userPass = user + ":" + pass

Dim TAuth As New MSXML2.XMLHTTP60

userPass = Base64Encode(userPass)
userPass = "Basic " + userPass

With TAuth
    .Open "POST", "https://testrail.<server>.com/index.php?/api/v2/get_case/3 HTTP/1.1", False
    .SetRequestHeader "Content-Type", "application/json"
    .SetRequestHeader "Accept", "application/json"
    .SetRequestHeader "Authorization", userPass
    .send
    sStatus = .Status
    sErg = .responseText

End With

现在我正在使用正确的用户名/密码变量，服务器地址准确且Base64Encode（）正常工作。

为什么我收到验证失败的错误？