Erro ao embutir Dataset em uma Classe

<canvas debug="true">

	<class name="testedata">

	  <dataset name="mydata">
		<myxml>
			<person show="simpsons">
			  <firstName>Homer</firstName>
			  <lastName>Simpson</lastName>
			</person>
			<person show="simpsons">
			  <firstName>Marge</firstName>
			  <lastName>Simpson</lastName>
			</person>
			<person show="simpsons">
			  <firstName>Montgomery</firstName>
			  <lastName>Burns</lastName>
			</person>
		  </myxml>
	  </dataset>

	  <method name="mostra">
	  	Debug.write(this);
	  	Debug.write(this.parent);
	  	Debug.write(this.mydata);
	  </method>
	  
	  <view name="mytable" oninit="this.parent.mostra()">
		<simplelayout axis="y" />
    <!--<view name="rowofdata" datapath="mydata:/myxml[1]/person">-->
	<!--<view name="rowofdata" datapath="this.parent.mydata:/myxml[1]/person">-->
	<!--<view name="rowofdata" datapath="this.mydata:/myxml[1]/person">-->
	<!--<view name="rowofdata" datapath="local:this.mydata:/myxml[1]/person">-->
    	<view name="rowofdata" datapath="local:mydata:/myxml[1]/person">
		  <simplelayout axis="x" />
		  <text datapath="firstName/text()" /> 
		  <text datapath="lastName/text()" /> 
		  <text datapath="@show" />
		</view>
	  </view>

	</class>

	<testedata name="mytesdata" />

</canvas>