Public Function validieren(ByVal file As String) As String
 
Dim result As String
Dim resulterrors As String
 
Dim header As String
 
'reset UI information 
[error] = ""
result = ""
resulterrors = ""
isValid = True
header = ""
 
Dim xml As New XmlTextReader(file)
Dim xsd As New XmlValidatingReader(xml)
Try
 
xsd.ValidationType = ValidationType.Schema
 
'and validation errors events go to... 
AddHandler xsd.ValidationEventHandler, AddressOf MyValidationEventHandler
 
'wait until the read is over, its occuring in a different thread - kinda like 
' when your walking to get a cup of coffee and your mind is in Hawaii 
While xsd.Read()
End While
 
' Check whether the document is valid or invalid. 
If isValid Then
header = "Document is valid"
Else
header = "Document is invalid"
End If
Catch a As UnauthorizedAccessException
'dont have access permission 
[error] = a.Message
Catch a As Exception
'and other things that could go wrong 
[error] = a.Message
Finally
    'Close the reader.
    If Not (xsd Is Nothing) Then
        xsd.Close()
    End If
 
End Try
resulterrors = [error]
result = header
validieren = "Result:" & result & vbCrLf & "Resulterrors:" & resulterrors
 
End Function
'handle our validation errors
Public Sub MyValidationEventHandler(ByVal sender As Object, ByVal args As _
  System.Xml.Schema.ValidationEventArgs)
    isValid = False
    [error] += args.Message + ControlChars.Lf + ControlChars.Lf
End Sub 'MyValidationEventHandler
 
End Module

Resultocument is invalid
Resulterrors:The attribute targetNamespace does not match the designated namespace URI. An error occurred at file:// ....blabla....in meinem Schema eben