UnityEngine._AndroidJNIHelper.GetFieldID not found ?

everything works fine until i import facebook audiance network sdk

then when I play the scene, it gives following error

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Exception: Field currentActivity or type signature not found
UnityEngine._AndroidJNIHelper.GetFieldID (System.IntPtr jclass, System.String fieldName, System.String signature, System.Boolean isStatic) (at C:/buildslave/unity/build/Modules/AndroidJNI/AndroidJava.cs:1445)
UnityEngine.AndroidJNIHelper.GetFieldID (System.IntPtr javaClass, System.String fieldName, System.String signature, System.Boolean isStatic) (at C:/buildslave/unity/build/Modules/AndroidJNI/AndroidJNI.bindings.cs:79)
UnityEngine._AndroidJNIHelper.GetFieldID[ReturnType] (System.IntPtr jclass, System.String fieldName, System.Boolean isStatic) (at C:/buildslave/unity/build/Modules/AndroidJNI/AndroidJava.cs:1358)
UnityEngine.AndroidJNIHelper.GetFieldID[FieldType] (System.IntPtr jclass, System.String fieldName, System.Boolean isStatic) (at C:/buildslave/unity/build/Modules/AndroidJNI/AndroidJNI.bindings.cs:172)
UnityEngine.AndroidJavaObject._GetStatic[FieldType] (System.String fieldName) (at C:/buildslave/unity/build/Modules/AndroidJNI/AndroidJava.cs:663)
UnityEngine.AndroidJavaObject.GetStatic[FieldType] (System.String fieldName) (at C:/buildslave/unity/build/Modules/AndroidJNI/AndroidJava.cs:274)
AudienceNetwork.AudienceNetworkAds.IsInitialized () (at Assets/AudienceNetwork/Library/AudienceNetworkAds.cs:33)
AudienceNetwork.AudienceNetworkAds.Initialize () (at Assets/AudienceNetwork/Library/AudienceNetworkAds.cs:15)
AdViewScene.Awake () (at Assets/AudienceNetwork/Scenes/Banner/AdViewScene.cs:26)
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cant find this specific error anywhere so cant find its solution.

did you found a solution for this problem?