Vb script encryption

set encData_byte As Byte() = New Byte(len( Request("txtPassword")) - 1) {}
  encData_byte = System.Text.Encoding.UTF8.GetBytes( Request("txtPassword"))
  set encodedData As String = Convert.ToBase64String(encData_byte)

The above code in VBSCRIPT for encryption runs fine while  debugging website ..
but fails to run in IIS


Please help