Why operators have no box?

[hooshbartar]

I used sample code of this project https://github.com/nephilimboy/Angular_FlowChartJS that I think uses your library to create a flow diagram. But what I see in my project is this:

Instead of this:

What is the problem and how can I fix it?
You can also find ,y project's code here: https://github.com/hooshbartar/test