Family overlapping / DragDrop

I need to check if the object I'm dragging is overlapping some other objects when I drop it. Somehow it works when checking for collision with another Family, but not with it's own. Here's a pic that shows what's working and what isn't. If I move the event out of the on Drop event, it works fine. How can I solve it?

<img src="http://i.imgur.com/TbSBwV9.png" border="0" />

Create another family with the same objects from ObjetosBuild:

Example:

• ObjetosBuild: Is overlapping ObjetosBuild2

Worked, thanks.