What do you mean, you want the bar to float over your head? or...
The bar, by default, should display your consumable value health.
To clear the target bar, you can press escape, or click on the ground, if I remember correctly.
Are you trying to give health bars to "interaction stuff" like boxes, doors, etc.?
Please give a few more examples, I'm sure I can help you out.
1) Maybe your target (are these NPCs? enemies?) have too small of collision boxes, for your mouse to click on, from a great distance?
2) Maybe your Player's select angle is not 360, or maybe the distance is set too low?