This can be due to a lot of things. First you have to know that clicking on a button will not only execute the action that is assigned as Success to that button (like showing an image) but also release the playhead. At least, if you use simple actions (Action accordion in the Properties panel). Did you use simple actions? Replacing simple actions by standard advanced actions can solve that, because the play head will not be released. Have a look at my video tutorial: http://www.youtube.com/watch?v=M3nKi-DB6Fw&feature=plcp
Secondly: pause for a button can be disabled in its properties panel. If you have no pause at all (no double vertical line on the button timeline) the play head will just continue. This you can check.
You have 3 buttons: are they staggered in the timeline or do they have their pausing point at the same moment? Could you post a screenshot of the timeline?
Lilybiri
