Ordering AI Allies Around?

Hi guys,

I had a question about ordering my AI allies around.  I know that if you click on any unit of your allies you get the different ping options (attack, stop, defend).  You click attack, you click an enemy planet the AI says "Gotit!"

But sometimes (most of the time, 90% of the time) when I do this, the AI says "Gotit!" but nothing happens.  One time, my ally had a huge fleet next to an undefended enemy asteroid.  It was that enemies last remaning asteroid, if he woudl have attacked we would have eliminated the bugger.  I selected that huge fleet, clicked attack, clicked the asteroid.  AI said "Gotit!"  but the AI sat around doing nothing.  It didn't jump.  I selected the units and pressed alt, to see what the orders were, they were attacking scouts and trade ships passing through the grav well.  Finally after upwards of 30 minutes!!!! the fleet finally jumped to the astroid, but by that time the enemy had reestablished himself at several other planets adding literally severaly hours to my game, as I had to dealing with issues on the main front while building a secondary fleet to fly out there and mop the mess up myself.

Is there a secret to issuing commands to your AI allies?  Sometimes it works, and they jump immediately where I ask them to.  Sometimes, they don't.  Sometimes they do 45 minutes later.  Sometimes they seem to get distracted on scouts and trade ships along the way.  Any clues about how this works? 

Maybe i have to select the specific units i'de like to be moved? Maybe I only have to click one unit?  Do they respond better when clicking on ships or structures rather than planets?  Perhaps because i told him to attack a planet, he didn't move in until he had massed a decent amount of seige frigs to join his fleet... which could easily take 30 minutes.    But I think his capships alone could've obliterated the asteroid in that time.

Any advice would be greatly appreciated.  As intelligent and responsive allies seem to make hte difference between a single player game being tons o' fun, and being filled with several hours of "if you want it done right you have to do it yourself" type action.

Thanks.