Flex :: 1020 Undefined Property Right After Associative Array Defined Via Var?

While developing with Adobe Flex, I'm working on my first application - and use pretty much actionscript.

In my mxml application, I include as3 file via <mx:Script source="as/myas3file.as></mx:Script>.

In myas3file.as, I include (thru include "variables.as";) file variables.as, which contains following code:

var timer:Object = new Object();
timer.t = 60;
or (in other test case)
var timer:Object = {t:60, j:"80"};
timer.t = 80;

Neither case works! Even if I rewrite example code from official documentation, it throws an 1020 error.