UnityとNCMBを使ってランキングを実装しようとしているが、エラーが出ます！

前提・実現したいこと

UnityでNCMBを使ってスコアランキングボードを作ろうとしています。

発生している問題・エラーメッセージ

ランキングデータをセーブしようとしたら、毎回こうなります。

UriFormatException: Invalid URI: The URI is empty.
System.Uri.CreateThis (System.String uri, System.Boolean dontEscape, System.UriKind uriKind) (at <ae22a4e8f83c41d69684ae7f557133d9>:0)
System.Uri..ctor (System.String uriString) (at <ae22a4e8f83c41d69684ae7f557133d9>:0)
NCMB.Internal.NCMBConnection..ctor (System.String url, NCMB.Internal.ConnectType method, System.String content, System.String sessionToken, NCMB.NCMBFile file, System.String domain) (at Assets/NCMB/Script/NCMBConnection.cs:112)
NCMB.Internal.NCMBConnection..ctor (System.String url, NCMB.Internal.ConnectType method, System.String content, System.String sessionToken) (at Assets/NCMB/Script/NCMBConnection.cs:93)
NCMB.NCMBObject.Save (NCMB.NCMBCallback callback) (at Assets/NCMB/Script/NCMBObject.cs:962)
NCMB.NCMBObject.SaveAsync (NCMB.NCMBCallback callback) (at Assets/NCMB/Script/NCMBObject.cs:890)
QuickRanking.SaveRanking (System.String name, System.Int32 score, UnityEngine.Events.UnityAction callback) (at Assets/Scripts/QuickRanking.cs:101)
BestScore.Save () (at Assets/BestScore.cs:24)
UnityEngine.Events.InvokableCall.Invoke () (at /Users/builduser/buildslave/unity/build/Runtime/Export/UnityEvent/UnityEvent.cs:166)
UnityEngine.Events.UnityEvent.Invoke () (at /Users/builduser/buildslave/unity/build/Runtime/Export/UnityEvent/UnityEvent/UnityEvent_0.cs:58)
UnityEngine.UI.Button.Press () (at /Applications/Unity/Hub/Editor/2019.3.0f4/Unity.app/Contents/Resources/PackageManager/BuiltInPackages/com.unity.ugui/Runtime/UI/Core/Button.cs:68)
UnityEngine.UI.Button.OnPointerClick (UnityEngine.EventSystems.PointerEventData eventData) (at /Applications/Unity/Hub/Editor/2019.3.0f4/Unity.app/Contents/Resources/PackageManager/BuiltInPackages/com.unity.ugui/Runtime/UI/Core/Button.cs:110)
UnityEngine.EventSystems.ExecuteEvents.Execute (UnityEngine.EventSystems.IPointerClickHandler handler, UnityEngine.EventSystems.BaseEventData eventData) (at /Applications/Unity/Hub/Editor/2019.3.0f4/Unity.app/Contents/Resources/PackageManager/BuiltInPackages/com.unity.ugui/Runtime/EventSystem/ExecuteEvents.cs:50)
UnityEngine.EventSystems.ExecuteEvents.Execute[T] (UnityEngine.GameObject target, UnityEngine.EventSystems.BaseEventData eventData, UnityEngine.EventSystems.ExecuteEvents+EventFunction`1[T1] functor) (at /Applications/Unity/Hub/Editor/2019.3.0f4/Unity.app/Contents/Resources/PackageManager/BuiltInPackages/com.unity.ugui/Runtime/EventSystem/ExecuteEvents.cs:261)
UnityEngine.EventSystems.EventSystem:Update() (at /Applications/Unity/Hub/Editor/2019.3.0f4/Unity.app/Contents/Resources/PackageManager/BuiltInPackages/com.unity.ugui/Runtime/EventSystem/EventSystem.cs:377)