Works now, but you seem to be using a third-party plugin "OR" so I can't open the file. If you can describe how you make the tank move, or reupload the file without the plugin, I can still try to help.
Or plugin is here: http://www.scirra.com/forum/plugin-or_topic47046.html
Can't remove the or plugin.
The working part of game is up here, you can play it with browser.
And the screenshot of enemy tank random movement.
<img src="http://www.upload.ee/image/2397372/tankc.PNG" border="0">
Sorry that variables and stuff aren't English