html5 discrepancy between desktop and idevice when evaluating null

if(%6,
			trace('%6 not empty');
			txtadd(hotspot[%1].onover,'tween(alpha,0.2);action_name(',%1,',',%6,',',%5,',',%7,',',%8,');');
		,
			trace('%6 empty');
			txtadd(hotspot[%1].onover,'tween(alpha,0.2);action_name(',%1,',',null,',',%5,',',%7,',',%8,');');
		);


<action name="action_name" >
if(%2,
	trace(%2 is empty');
,
	trace(%2 is not empty');
);
if(%2 == null,
	trace('%2 is null');
,
	trace( %2 is not null');


);
</action>