XML Schema Validator in VB.NET

Private Sub validate_Click(ByVal sender As Object, ByVal e As System.EventArgs)
'reset UI information
[error] = ""
result.Text = ""
resultErrors.Text = ""
isValid = True
header = ""
Try
Dim xml As New XmlTextReader(file.Text)
Dim xsd As New XmlValidatingReader(xml)
'use schemas or DTDs
If documentTypeSchema.Checked = True Then
'schemas - YAAAAAAA
xsd.ValidationType = ValidationType.Schema
Else
If documentTypeNone.Checked = True Then
'so you just want to see if your XML is well formed?
xsd.ValidationType = ValidationType.None
Else
'why do you want to learn this? its old, no one uses it and they are laughing behind your back. Shame on you!
xsd.ValidationType = ValidationType.DTD
End If
End If '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
xsd.Close()
' 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
End Try
resultErrors.Text = [error]
result.Text = header
End Sub 'validate_Click