我正在尝试从GitHub运行最新的Unity Watson SDK。每当我尝试播放示例场景进行文字语音转换时，都会出现此错误。我已经设置了API密钥，我所在的地区是美国达拉斯，但我认为这与问题无关。
我正在为Android开发一个利用语音文本的应用程序。我尝试查找了几个小时，但找不到解决方案。我尝试重新下载SDK，但没有任何改变。
[02/03/2019 00:54:42][Unity][CRITICAL] Unity Exception
ArgumentOutOfRangeException: Length cannot be less than zero.
Parameter name: length : System.String.Substring (System.Int32
startIndex, System.Int32 length) (at
<f2e6809acb14476a81f399aeb800f8f2>:0)
IBM.Watson.DeveloperCloud.Connection.RESTConnector.AddHeaders
(System.Collections.Generic.Dictionary`2[TKey,TValue] headers)
(at Assets/unity-sdk-
2.14.0/Scripts/Connection/RESTConnector.cs:380)
IBM.Watson.DeveloperCloud.Connection.RESTConnector+
<ProcessRequestQueue>c__Iterator0.MoveNext () (at Assets/unity-sdk-
2.14.0/Scripts/Connection/RESTConnector.cs:470)
IBM.Watson.DeveloperCloud.Utilities.Runnable+Routine.MoveNext ()
(at Assets/unity-sdk-2.14.0/Scripts/Utilities/Runnable.cs:131)
UnityEngine.SetupCoroutine.InvokeMoveNext
(System.Collections.IEnumerator enumerator, System.IntPtr
returnValueAddress)
(at
/Users/builduser/buildslave/unity/build/Runtime/Export/Coroutines.cs:17)
UnityEngine.Debug:LogError(Object)
IBM.Watson.DeveloperCloud.Debug.DebugReactor:ProcessLog(LogRecord)
(at Assets/unity-sdk-2.14.0/Scripts/Debug/DebugReactor.cs:60)
IBM.Watson.DeveloperCloud.Logging.LogSystem:ProcessLog(LogRecord)
(at Assets/unity-sdk-2.14.0/Scripts/Logging/Logger.cs:206)
IBM.Watson.DeveloperCloud.Logging.Log:Critical(String, String,
Object[]) (at Assets/unity-sdk-2.14.0/Scripts/Logging/Logger.cs:294)
IBM.Watson.DeveloperCloud.Logging.LogSystem:UnityLogCallback(String,
String, LogType) (at Assets/unity-sdk-
2.14.0/Scripts/Logging/Logger.cs:167)
UnityEngine.Application:CallLogCallback(String, String, LogType,
Boolean)
我知道场景应该输出我认为的内容，但是什么也没有发生。任何帮助将不胜感激！