[2005] String.Concat generates a string but issuse a format not supported exception -

I need help with this perplexing problem.

The following is ment to generate the path to a text file and stream the data found there into an array.

Dim y1 As String
Dim y2 As String
Dim y3 As String
Dim path As String
Dim b1 As String
Dim b2 As String
Dim z As Integer

y1 = ("L:\Gossary\ListBox")
y2 = (" data.txt")
b1 = ("(")
b2 = (")")
z = ListBox1.SelectedIndex
y3 = z.ToString
path = String.Concat(b1 + y1 + y3 + y2 + b2)
Using MyReader As New Microsoft.VisualBasic.FileIO.TextFieldParser(path)


MyReader.TextFieldType = FileIO.FieldType.Delimited
MyReader.SetDelimiters("@")

Dim currentRow As String()
While Not MyReader.EndOfData
Try
currentRow = MyReader.ReadFields()
Dim currentField As String
For Each currentField In currentRow
CurrentFieldArray.Add(currentField)
LblSource1.Text = currentField
Next
Catch ex As _
Microsoft.VisualBasic.FileIO.MalformedLineException
MsgBox("Line " & ex.Message & _
"is not valid and will be skipped.")

End Try
End While
End Using

However this produces the following exception:

"The given path's format is not supported."