Strange bug (ArgumentError #1112) in extending MediaTraitBase

Question

Hello.
I'm implementing a custom dynamic stream trait, which allows to use stream switching with standard progressive video.
When I create the Trait (in the proxy element) a runtime error is thrown:
ArgumentError: Error #1112: Discordancia del recuento de argumentos en coerción de clase.  Se esperaba 1; se obtuvo 4.
at MyDynamicStreamTrait$cinit()
at global$init()[MyDynamicStreamTrait.as:20]
The constructor is not even being executed.
Here are relevant extract of the code:
========= MyVideoElement.as ======================
public class MyVideoElement extends ProxyElement {
/*(in set wrappedElement):*/
function processTraitAdd( type:String ):void {
if (type == MediaTraitType.TIME) {
var mytt:MyTimeTrait = new MyTimeTrait(loadTrait.netStream, wrappedElement.resource)
addTrait( type, mytt );
mydst = new MyDynamicStreamTrait(wrappedElement.resource, mytt, loadTrait);
addTrait( MediaTraitType.DYNAMIC_STREAM, mydst);

Answer 1

(sorry, I was in Eclipse-mode and hit Ctrl-S)
============= MyDynamicStreamTrait.as ==================
public class MyDynamicStreamTrait extends MediaTraitBase
public function MyDynamicStreamTrait( resource:URLResource = null, timeTrait:MyTimeTrait = null, loadTrait:MyLoadTrait = null )
super( MediaTraitType.DYNAMIC_STREAM );
this._timeTrait = timeTrait;
this._loadTrait = loadTrait;
this._netStream = loadTrait.netStream;
this._resource = resource;
trace( 'created' );
/* various logic */
============================================================
As soon as the 'new MyDynamicStreamTrait(wrappedElement.resource, mytt, loadTrait);' statement is executed, the ArgumentError is thrown.
None of my other trait extensions is behaving this way.
Any idea on what's happening?