Please read the documentation of this addon before reporting bugs. And please make at least a screenshot to show us the issue - we have to spend too much time to search for a small button somewhere in the gui to find it.
In your case I found the issue very easily: Just hover over the "shape" combobox you can see the hint that you "need at least three levels of branching" before it is activated. So go to "branch splitting" set "Levels" to 3 and all will be fine..
Closing your report now...