SOAP API Error 400 Bad Request

We're seeing some strange results when attempting to create a resource using the SOAP API.

Here is the URL that we are attempting to send data to: https://secure.eloqua.com/API/1.2/Service.svc. And this is the SOAP action: https://secure.eloqua.com/API/1.2/DynamicEntityService/Create.

The following is an example of the XML that we are sending over:

<?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://secure.eloqua.com/API/1.2" xmlns:env="http://schemas.xmlsoap.org/soap/envelope/" xmlns:arr="http://schemas.microsoft.com/2003/10/Serialization/Arrays">  <env:Header>  <wsse:Security xmlns:wsse="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd">  <wsse:UsernameToken wsu:Id="UsernameToken-1" xmlns:wsu="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd">  <wsse:Username>username_here</wsse:Username>  <wsse:Password Type="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-username-token-profile-1.0#PasswordText">password_here</wsse:Password>  </wsse:UsernameToken>  </wsse:Security>  </env:Header>  <env:Body>  <wsdl:Create>  <entities>  <DynamicEntity>  <EntityType>  <wsdl:ID>29</wsdl:ID>  <wsdl:Name>Email Sign Up</wsdl:Name>  <wsdl:Type>Form</wsdl:Type>  </EntityType>  <wsdl:FieldValueCollection>  <EntityFields>  <wsdl:InternalName>Contact0Email</wsdl:InternalName>  <wsdl:Value>test@example.com</wsdl:Value>  </EntityFields>  <EntityFields>  <wsdl:InternalName>Contact0FirstName</wsdl:InternalName>  <wsdl:Value>John</wsdl:Value>  </EntityFields>  <EntityFields>  <wsdl:InternalName>Contact0LastName</wsdl:InternalName>  <wsdl:Value>Smith</wsdl:Value>  </EntityFields>  <EntityFields>  <wsdl:InternalName>FormID</wsdl:InternalName>  <wsdl:Value>29</wsdl:Value>  </EntityFields>  </wsdl:FieldValueCollection>  </DynamicEntity>  </entities>  </wsdl:Create>  </env:Body></env:Envelope>

The response that we get back is a 400 response which signifies a bad request.

We're hoping to get answers to the following:

Is this endpoint still the endpoint that we should be using to send data to?
Is the schema that we are using the correct schema? If not, what are we missing?