If you look carefully at the pause point of the button on the slide, you'll see that it is pausing the play before your clickbox has been added to the timeline. This will mean your click box won't work until AFTER your button gets clicked.
Since clickboxes are invisible, you can usually just have them begin from the start of the slide and go right to the end unless you need to have them pause the slide at some point. Unlike buttons which show their pause points as a vertical line in the middle of the object on their layer, the pause point of a click box is right at the end of the object representing it on the timeline layer. So to make a slide pause with a click box you have to drag its ending point forward to the point where the pause should happen.
Another thing to check is that if you want your captions to be fully visible when the button object pauses play, you need to ensure the pause doesn't happen before they've finished fading in.
The 'ghost' text caption's timeline is not visible on your screenshot. I suspect it is just on top of the click box (no problem), and starting little bit before the click box (from the small portion visible on top of the click box timeline), and that it has the default transition Fade in/Fade out. So, as Rod points out, the pausing caused by the button occurs somewhere during the fade in transition of the Text Caption 'Click on the Post...'
What is the function of Button_15? Is it a navigational button? And you want the user to be able to use the click box? If that is correct, make sure that the click box pausing occurs before the button pausing point. You can control the pausing point of the button in the Properties panel (Timing) or you can drag it on the timeline. To control the pausing of the click box, you have to make its timeline shorter (it is 'almost' at the end of its timeline).
Thanks for your responses. IT was a time line issue with the inactive/active section of buttons.
I've got another problem with a let's call it a 'ghost image'.
It's a screen shot of a previous slide which is now appearing on my slides but not in the time line or in the film strip view.
If I create a new slide it seems to put this ghost image on that slide.
I've tried closing down and trying it again but the issue is still there.
Have attached an image showing a new blank slide I've put in, and that square workflow image just appears for no reason, but you can't see it on the film stip view (slide 10)
This image is also appear on the previous 4 slides only.
Hopefully you can see it - tad small!