This error is driving me crazy

Private Sub BuildPostData(ByteArray() As Byte, ByVal strPostData As String)
    Dim intNewBytes As Integer
    Dim strCH As String
    Dim i As Integer
    
    intNewBytes = Len(strPostData) - 1
    
    If intNewBytes < 0 Then
     Exit Sub
    End If
    
    ReDim ByteArray(intNewBytes)
    
    For i = 0 To intNewBytes
     strCH = Mid$(strPostData, i + 1, 1)
     
     If strCH = Space(1) Then
        strCH = "+"
     End If
     
     ByteArray(i) = Asc(strCH)
    Next
End Sub

Private Sub Command1_Click()
    Dim strPostData As String
    Dim strHeader As String
    Dim varPostData As Variant
        
    'Make the Post Data String
    strPostData = "Name1=Value1&Name2=Value2"
    
    'Pack the post data into a byte array
    BuildPostData bytpostdata(), strPostData
    
    'Write the byte into a variant
    varPostData = bytpostdata
    
    'Create the Header
    strHeader = "Content-Type: application/x-www-form-urlencoded" + Chr(10) + Chr(13)
    
    'Post the data
    Web.Navigate2 "http://mysite.com", 0, "", varPostData, strHeader
End Sub