Got it!!! Take a look:

VB code:

' vendor and product IDs
Private Const VendorID = 6017
Private Const ProductID = 2000

' read and write buffers
Private Const BufferInSize = 8
Private Const BufferOutSize = 8
Dim BufferIn(0 To BufferInSize) <---Mistake here, need to declare as byte !!!
Dim BufferOut(0 To BufferOutSize)
Dim voltaje As String

------------------------------------------------------------

I need to write 1000 lines with the next message:

"Dont forget declaration of variables" LOL