Skype for Business Server 2015 - 准备 Active Directory 失败并出现错误：5

我正在尝试按照本指南将 Skype for Business 2015 部署到测试实验室。我已经执行了准备 Active Directory 之前的所有先决条件操作。当我从部署向导运行任务以准备 AD 架构时，它失败并在日志中显示以下错误消息。

Error: Upload C:\Program Files\Skype for Business Server 2015\Deployment\Setup\ExternalSchema.ldf failed. The exit code is "5".
▼ Details
└ Type: DeploymentException
    └ ▼ Stack Trace
    └   at Microsoft.Rtc.Management.Deployment.LcSchema.ThrowLDIFDE_ErrorCodeDeploymentException(String path, Int32 exitCode) 
        at Microsoft.Rtc.Management.Deployment.LcSchema.UploadSchema(String path) 
        at Microsoft.Rtc.Management.Deployment.LcSchema.PrepareSchema(String ldf, SchemaType schemaType) 
        at Microsoft.Rtc.Management.Deployment.Tasks.ServerSchemaPrepareTask.Action()

我可以确认我作为Schema Admins组的成员运行。