Not managing to set x,y coordinates of a form element...

I have a PDF with an intro tutorial compounded by 5 small custom popups distributed on separate layers. The popups has a close button. As a popup is closed the next one is shown and so on. Because I use the very same close button for all the popups (and the poppus will show up in different places on the screen) I have to move the close button accordingly. However I am no managing to do this...

I tried:

this.getField("btnClose").style.left = "7.82in";
this.getField("btnClose").style.bottom = "7.47in";
this.getField("btnClose").style.right = "8.04in";
this.getField("btnClose").style.top = "7.69in";

But then it caused a sintaxe error (I think it didn't like the 'style' property). Then I tried:

this.getField("btnClose").left = "7.82in";
this.getField("btnClose").bottom = "7.47in";
this.getField("btnClose").right = "8.04in";
this.getField("btnClose").top = "7.69in";

As you may noticed I remove the 'style' so it didn't raise the error but also didn't move my button.

PS: I tried to use "px" instead "in" but it didn't produce any effect (the button still doesn't move)

I am using Acrobat XI.

Any idea?

Thanks!