[Geotools-gt2-users] Error: The type WrongPathException is not visible

[wbh <wan...@16...>]

Hi guys,
I am trying to use Astar algorithm and have my code like this:
Path astarPath;
try {
astarPath = astar.getPath();
}
 catch (WrongPathException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
To my surprise, the compiler reports the error: The type WrongPathException is not visible.
But this class does exist at the package org.geotools.graph.path....
What makes my confuse is that I used AstarShortestPahtFinder in another function in the same class, it does not need to throw this exception.
Can anyone tell me why?
Thx.