Public Key Error WCF Client - wcf

Question

I am working on a WCF service. It is hosted in IIS and secured by SSL. I am using custom biding with Soap11. I have a private key for this service and it is referenced in the web.config file. I have exported the public key from the private key and plan to give this public key to a vendor who will call this service.
When I try to test the service using a client. I am getting the below error. In my client I have referenced the public key. My client is sending the request to the service which is secured by the private key. I have checked the private key to make sure I have "you have a private key that correspond to this certificate. also, i have the IIS app pool running under my user name. I am the administrator in the computer.
However, when i try to send a request, I get the error "The private key is not present in the X.509 certificate." in the client. What could be causing this error?
Stack Trace:
System.NotSupportedException was caught
HResult=-2146233067
Message=The private key is not present in the X.509 certificate.
Source=mscorlib
StackTrace:
Server stack trace:
at System.IdentityModel.Tokens.X509AsymmetricSecurityKey.GetSignatureFormatter(String algorithm)
at System.IdentityModel.SignedXml.ComputeSignature(SecurityKey signingKey)
at System.ServiceModel.Security.WSSecurityOneDotZeroSendSecurityHeader.CompletePrimarySignatureCore(SendSecurityHeaderElement[] signatureConfirmations, SecurityToken[] signedEndorsingTokens, SecurityToken[] signedTokens, SendSecurityHeaderElement[] basicTokens, Boolean isPrimarySignature)
at System.ServiceModel.Security.SendSecurityHeader.CompleteSignature()
at System.ServiceModel.Security.SendSecurityHeader.CompleteSecurityApplication()
at System.ServiceModel.Security.SecurityAppliedMessage.OnWriteMessage(XmlDictionaryWriter writer)
at System.ServiceModel.Channels.BufferedMessageWriter.WriteMessage(Message message, BufferManager bufferManager, Int32 initialOffset, Int32 maxSizeQuota)
at System.ServiceModel.Channels.TextMessageEncoderFactory.TextMessageEncoder.WriteMessage(Message message, Int32 maxMessageSize, BufferManager bufferManager, Int32 messageOffset)
at System.ServiceModel.Channels.HttpOutput.SerializeBufferedMessage(Message message)
at System.ServiceModel.Channels.HttpOutput.Send(TimeSpan timeout)
at System.ServiceModel.Channels.HttpChannelFactory`1.HttpRequestChannel.HttpChannelRequest.SendRequest(Message message, TimeSpan timeout)
at System.ServiceModel.Channels.RequestChannel.Request(Message message, TimeSpan timeout)
at System.ServiceModel.Channels.SecurityChannelFactory`1.SecurityRequestChannel.Request(Message message, TimeSpan timeout)
at System.ServiceModel.Dispatcher.RequestChannelBinder.Request(Message message, TimeSpan timeout)
at System.ServiceModel.Channels.ServiceChannel.Call(String action, Boolean oneway, ProxyOperationRuntime operation, Object[] ins, Object[] outs, TimeSpan timeout)
at System.ServiceModel.Channels.ServiceChannelProxy.InvokeService(IMethodCallMessage methodCall, ProxyOperationRuntime operation)
at System.ServiceModel.Channels.ServiceChannelProxy.Invoke(IMessage message)
Exception rethrown at [0]:
at System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage(IMessage reqMsg, IMessage retMsg)
at System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData& msgData, Int32 type)
at PaymentGatewayTestClient.Customer.ICustomerDetails.CustomerDetails(CustomerDetailRequest request)
at PaymentGatewayTestClient.Customer.CustomerDetailsClient.CustomerDetails(CustomerDetailRequest request) in c:\temp\Test\PaymentGatewayTestClient\PaymentGatewayTestClient\Service References\Customer\Reference.cs:line 937
at PaymentGatewayTestClient.Program.Main(String[] args) in c:\temp\Test\PaymentGatewayTestClient\PaymentGatewayTestClient\Program.cs:line 38
InnerException:

Answer 1

It looks like the server can't access the private part of the key. You have to grant permission to the private key for the user that runs your app pool.
Also see this:
PrivateKey trust permissions for local machine "Trusted roots" certificates