using LAPSE Plus in Eclipse

After installing the LAPSE Plus following this website. An error may occur when you click the Find sinks in the view of Vulnerability Sinks as below,

An internal error occurred during: "Computing Sinks". java.lang.NullPointerException

It is because you need to click Find sources in the view of Vulnerability Sources and wait it to finish first. After that, you click Find sinks, and there will be no error.