|   | 1 |  initial version  | 
As documented here, ProtoField.int16 and ProtoField.newhave their 2 first parameters swapped. So what you see is normal, you need to modify your ProroField.new function call.
|   | 2 |  No.2 Revision  | 
As documented here, ProtoField.int16 and ProtoField.newhave ProtoField.new have their 2 first parameters swapped. So what you see is normal, you need to modify your ProroField.new ProtoField.new function call.