XML : What I'm missing on sending to WSDL?

I'm developing an application which interacts with bing ads api, here is endpoint description: https://msdn.microsoft.com/en-us/library/bing-ads-campaign-management-addadextensions

I'm sending this XML:

  <?xml version="1.0" encoding="UTF-8"?>  <env:Envelope xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:tns="https://bingads.microsoft.com/CampaignManagement/v9" xmlns:env="http://schemas.xmlsoap.org/soap/envelope/" xmlns:arr="http://schemas.microsoft.com/2003/10/Serialization/Arrays">    <env:Header>      <tns:UserName>API_project_test</tns:UserName>      <tns:Password>***FILTERED***</tns:Password>      <tns:DeveloperToken>***FILTERED***</tns:DeveloperToken>      <tns:CustomerId>1147374</tns:CustomerId>      <tns:CustomerAccountId>434383475</tns:CustomerAccountId>    </env:Header>    <env:Body>      <tns:AddAdExtensionsRequest>        <tns:AdExtensions xmlns:i="http://www.w3.org/2001/XMLSchema-instance">          <tns:AdExtension>            <tns:ForwardCompatibilityMap xmlns:a="http://schemas.datacontract.org/2004/07/System.Collections.Generic"/>            <tns:SiteLinks>              <tns:SiteLink>                <tns:DestnationUrl>http://sterkonix.cz</tns:DestnationUrl>                <tns:DisplayText>Hello world</tns:DisplayText>              </tns:SiteLink>            </tns:SiteLinks>          </tns:AdExtension>        </tns:AdExtensions>      </tns:AddAdExtensionsRequest>    </env:Body>  </env:Envelope>    

And I'm getting this kind of error:

  SOAP response (status 500):  <s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/"><s:Body><s:Fault><faultcode xmlns:a="http://schemas.microsoft.com/net/2005/12/windowscommunicationfoundation/dispatcher">a:InternalServiceFault</fau  ltcode><faultstring xml:lang="en-US">Cannot create an abstract class.</faultstring><detail><ExceptionDetail xmlns="http://schemas.datacontract.org/2004/07/System.ServiceModel" xmlns:i="http://www.w3.org/2001/XMLS  chema-instance"><HelpLink i:nil="true"/><InnerException i:nil="true"/><Message>Cannot create an abstract class.</Message><StackTrace>   at System.Runtime.Serialization.FormatterServices.nativeGetUninitializedObje  ct(RuntimeType type)&#xD;     at ReadAdExtensionFromXml(XmlReaderDelegator , XmlObjectSerializerReadContext , XmlDictionaryString[] , XmlDictionaryString[] )&#xD;     at System.Runtime.Serialization.ClassDataContract.ReadXmlValue(XmlReaderDelegator xmlReader, XmlObjectSerializerReadContext context)&#xD;     at System.Runtime.Serialization.XmlObjectSerializerReadContext.InternalDeserialize(XmlReaderDelegator reader, String name, String ns, Type declaredType, DataContract&amp; dataContract)&#xD;     at System.Runtime.Serialization.XmlObjectSerializerReadContext.InternalDeserialize(XmlReaderDelegator xmlReader, Int32 id, RuntimeTypeHandle declaredTypeHandle, String name, String ns)&#xD;     at ReadArrayOfAdExtensionFromXml(XmlReaderDelegator , XmlObjectSerializerReadContext , XmlDictionaryString , XmlDictionaryString , CollectionDataContract )&#xD;     at System.Runtime.Serialization.CollectionDataContract.ReadXmlValue(XmlReaderDelegator xmlReader, XmlObjectSerializerReadContext context)&#xD;     at System.Runtime.Serialization.XmlObjectSerializerReadContext.InternalDeserialize(XmlReaderDelegator reader, String name, String ns, Type declaredType, DataContract&amp; dataContract)&#xD;     at System.Runtime.Serialization.XmlObjectSerializerReadContext.InternalDeserialize(XmlReaderDelegator xmlReader, Type declaredType, DataContract dataContract, String name, String ns)&#xD;     at System.Runtime.Serialization.DataContractSerializer.InternalReadObject(XmlReaderDelegator xmlReader, Boolean verifyObjectName, DataContractResolver dataContractResolver)&#xD;     at System.Runtime.Serialization.XmlObjectSerializer.ReadObjectHandleExceptions(XmlReaderDelegator reader, Boolean verifyObjectName, DataContractResolver dataContractResolver)&#xD;     at System.Runtime.Serialization.DataContractSerializer.ReadObject(XmlDictionaryReader reader, Boolean verifyObjectName)&#xD;     at System.ServiceModel.Dispatcher.DataContractSerializerOperationFormatter.PartInfo.ReadObject(XmlDictionaryReader reader, XmlObjectSerializer serializer)&#xD;     at System.ServiceModel.Dispatcher.DataContractSerializerOperationFormatter.DeserializeParameterPart(XmlDictionaryReader reader, PartInfo part, Boolean isRequest)&#xD;     at System.ServiceModel.Dispatcher.DataContractSerializerOperationFormatter.DeserializeParameters(XmlDictionaryReader reader, PartInfo[] parts, Object[] parameters, Boolean isRequest)&#xD;     at System.ServiceModel.Dispatcher.DataContractSerializerOperationFormatter.DeserializeBody(XmlDictionaryReader reader, MessageVersion version, String action, MessageDescription messageDescription, Object[] par  ameters, Boolean isRequest)&#xD;     at System.ServiceModel.Dispatcher.OperationFormatter.DeserializeBodyContents(Message message, Object[] parameters, Boolean isRequest)&#xD;     at System.ServiceModel.Dispatcher.OperationFormatter.DeserializeRequest(Message message, Object[] parameters)&#xD;     at System.ServiceModel.Dispatcher.DispatchOperationRuntime.DeserializeInputs(MessageRpc&amp; rpc)&#xD;     at System.ServiceModel.Dispatcher.DispatchOperationRuntime.InvokeBegin(MessageRpc&amp; rpc)&#xD;     at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage5(MessageRpc&amp; rpc)&#xD;     at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage31(MessageRpc&amp; rpc)&#xD;     at System.ServiceModel.Dispatcher.MessageRpc.Process(Boolean isOperationContextSet)</StackTrace><Type>System.MemberAccessException</Type></ExceptionDetail></detail></s:Fault></s:Body></s:Envelope>    

What do I need to send to prevent bingads wsdl from refusing my xml?