c# - XMLDocument.Validate Error: System.InvalidOperationException : The XmlSchemaSet on the document is either null or has no schemas in it -

When I wanted to verify my in-memory xml schema, I found this strange error, did I do anything wrong?

  [Test] Public Zero Validation XML () {int errorCount = 0; On xmlString = "& lt ;? xml version = '1.0'> ?? 
 response & gt; error code = '1' & gt; success & lt; / error & gt; & lt; / Reaction & gt; "; XmlDocument xmlDocument = New XmlDocument (); XmlDocument.LoadXml (xmlString); XmlDocument.Validate ((sender, e) = & gt; error code +); Assurance First (0, error code); }  

The exception was:

  failed: System.InvalidOperationException: XmlSchemaSet on the document is either empty or has a schema in it. Provide schema information before making a valid call System.Xml.XmlDocument.Validate (ValidationEventHandler validationEventHandler)  

You are trying to validate a schema describing XmlDocument

  xmlDocument .Schemas.Add (New XmlSchema ());  

To verify it in front of an empty schema (as opposed to zero) and verification will fail (instead of throwing an exception), 1 to set ERRORCOUNT tries to.