Hi, thank you for downloading astah* community 6.3.

This option is available only in astah* professional and astah* UML editions.

Does astah* give you any alert dialog when you fail saving a file? If so, what does it say?
Also let us know the environment that you run astah* on such as OS, Java version etc.
Your log file can be found in USER_HOME\.astah\community\astah_com.log

Thanks.
Satomi