Hi @Chao
Development of the CommonApproach DRS was discontinued when iolite v4 was announced. The version of the CommonApproach DRS that was released was a beta version only, and you should not trust the results.
The VizualAge_UcomPbine DRS can handle common-Pb bearing samples for U-Pb geochron. It is available from Joe's GitHub page: https://github.com/japetrus/VizualAge_UcomPbine
Joe has incorporated the differences between UcomPbine and the CommonApproach in iolite v4, which is what we now recommend.
Best regards,
Bence