How are you handling "according to number picked".. are you assigning the # to a variable then using a spawner system to spawn based on this variable value?
If your picking the number and selecting the objects in the same event it may get wonky.. seems like I ran into that same issue making the shooter in my sig. I ended up making number pickers (I use "choose" 1-10 instead of random.. but its all randoms) and then my spawner events fire off based on results in separate events.
Make a text item on your layout called debug and set it to "set text" whatever your &randomVariable is and you will be able to at least rule out if your randomizer is working.