CryptographicException APNS

[CryptographicException: An internal error occurred.
]
   System.Security.Cryptography.CryptographicException.ThrowCryptographicException(Int32 hr) +33
   System.Security.Cryptography.X509Certificates.X509Utils._LoadCertFromBlob(Byte[] rawData, IntPtr password, UInt32 dwFlags, Boolean persistKeySet, SafeCertContextHandle& pCertCtx) +0
   System.Security.Cryptography.X509Certificates.X509Certificate.LoadCertificateFromBlob(Byte[] rawData, Object password, X509KeyStorageFlags keyStorageFlags) +203
   System.Security.Cryptography.X509Certificates.X509Certificate..ctor(Byte[] rawData, String password) +80
   System.Security.Cryptography.X509Certificates.X509Certificate2..ctor(Byte[] rawData, String password) +79
   JdSoft.Apple.Apns.Notifications.NotificationConnection.start(String p12File, String p12FilePassword) +224
   JdSoft.Apple.Apns.Notifications.NotificationService.set_Connections(Int32 value) +119
   JdSoft.Apple.Apns.Notifications.NotificationService..ctor(Boolean sandbox, String p12File, String p12FilePassword, Int32 connections) +211
   APN.Page_Load(Object sender, EventArgs e) in c:\inetpub\wwwroot\iPhone\APN.aspx.cs:51
   System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +14
   System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +35
   System.Web.UI.Control.OnLoad(EventArgs e) +91
   System.Web.UI.Control.LoadRecursive() +74
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +2207

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use code in NotificationConnection.cs: 

//certificate = new X509Certificate2(System.IO.File.ReadAllBytes(p12File), p12FilePassword);
certificate = new X509Certificate2(System.IO.File.ReadAllBytes(p12File), p12FilePassword, X509KeyStorageFlags.MachineKeySet | X509KeyStorageFlags.PersistKeySet | X509KeyStorageFlags.Exportable);