Bokeh, what?

I recently read an article on bokeh. For those who don't know what it is, here's a dictionary definition of it: (originated from Japanese) it is the aesthetic quality of blur. 
I saw some really creative bokeh on tumblr in the shape of hearts and stars and was really intrigued in re-creating it with my christmas tree lights. But... errmm... why does mine look so weird? I can see the outline of the heart shaped cut-out but my bokeh isn't in the shape of it. poop. 

           This is  what it was suppose to be. Can anyway help me out?                     

(last image via Kiki Angel Encinas)