Validate xml files from subfolders

Hi All,

Presently I am browsing to a folder which contains xml files. futher i do validation against xsd.
But now I have to do some thing like this: When i select say folder1 in the subfolder1, subfolder2 and so on. these subfolders contains xml file which i have to validate against xsd. How do my code select files from subfolders and futher validation?

My code:

VB Code:

Private Sub btnInputXMLFile_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnInputXMLFile.Click
 Dim foldername As String
            Dim filename As String
            If FolderBrowserDialog1.ShowDialog() = DialogResult.OK Then
                foldername = FolderBrowserDialog1.SelectedPath()
            Else
                Dim Results As DialogResult = FolderBrowserDialog1.ShowDialog
                If Results = DialogResult.Cancel Then
                    Return
                End If
                Exit Sub
            End If
            mstrFolderXMLFiles = FolderBrowserDialog1.SelectedPath()
            txtInputXMLFile.Text = foldername
        End If
                validatexmls(mstrFolderXMLFiles)
End sub
Private Function validatexmls(ByVal infile As String) As Boolean
        Dim filename As String
 
        Dim mydir As New DirectoryInfo(infile)
        Dim m_xmld As XmlDocument
 
        Dim f As FileInfo() = mydir.GetFiles("*.xml")
        Dim i, j As Integer
        Try
            If RadioButton2.Checked Then
 
                For i = 0 To f.Length - 1
                    filename = f(i).FullName
                    ' create xml doc
                    m_xmld = New XmlDocument
                    m_xmld.Load(filename)
 
                    'First we create the xmltextreader
                    Dim xmlr As New XmlTextReader(filename)
                    Dim sc As XmlSchemaCollection = New XmlSchemaCollection
                    AddHandler sc.ValidationEventHandler, AddressOf ValidationCallBack
                    sc.Add(Nothing, mstrInputXSDFile.Trim)
                    'We pass the xmltextreader into the xmlvalidatingreader
                    'This will validate the xml doc with the schema file
                    'NOTE the xml file it self points to the schema file
                    Dim xmlvread As New XmlValidatingReader(xmlr)
                    xmlvread.ValidationType = ValidationType.Schema
                    xmlvread.Schemas.Add(sc)
                    ' Set the validation event handler
                    AddHandler xmlvread.ValidationEventHandler, AddressOf ValidationCallBack
                    m_success = True 'make sure to reset the success var
 
                    ' Read XML data
                    While (xmlvread.Read)
                    End While
                    'Close the reader.
                    xmlvread.Close()
                Next
                If m_success Then
                    WriterBox.Text = "No Validation Errors"
                Else
                    MsgBox("Validation Errors")
                End If
            End If
 
        Catch a As UnauthorizedAccessException
            'dont have access permission
            m_success = a.Message
        Catch a As Exception
            'and other things that could go wrong
            m_success = a.Message
        End Try
        'The validationeventhandler is the only thing that would
        'set m_Success to false
        Return m_success
    End Function