Save file with saveFileDialog1 in VB 2015

I am developing a desktop application that after some processes I need to record two files. To do this in a "SAVE" button I linked it to a SaveFileDialog where the operator enters the final name of the file.
What I need to do is save the file as the operator puts it, and at the same time I need to record the same file with some modifications in both the content and the file name.
That is, if the operator gives the file the name:
"exit202.cut" (the files have that extension) I also need to record the "exit202-test.cut".
The first file records it perfect, but I'm having a problem generating the second file. That's what I'm doing for the first file:

Dim Archivo As StreamWriter = File.CreateText(saveFileDialog1.FileName)
        'Agregagamos El Texto
        If IsNothing(txtVCUT.Text) = False Then
            Archivo.WriteLine(txtVCUT.Text)

            'Borra todos los búferes del sistema de escritura actual 
            Archivo.Flush()
            'Cierra el actual objeto StreamWriter 
            Archivo.Close()
        End If

Then I made for the second file:

Dim ArchivoTest As StreamWriter = File.CreateText(System.IO.Path.GetFileNameWithoutExtension(saveFileDialog1.FileName) & "-test.cut")

        If IsNothing(txtTEST.Text) = False Then
            ArchivoTest.WriteLine(txtTEST.Text)

            'Borra todos los búferes del sistema de escritura actual 
            ArchivoTest.Flush()
            'Cierra el actual objeto StreamWriter 
            ArchivoTest.Close()
        End If

I get the name of the file that was put in the SaveFileDialog and I "arm" the last part of the file adding "-test.cut"
Well ... the result is that it does not record anything at all ... does anyone have experience with this control, so that it can give me a hand?