[TYPO3-english] do XCLASS from other class which is included in main class

[May Dara]

Dear TYPO3 Group,

I have one problem with XCLASS:
Does somebody know XCLASS can extend other class which is included and 
used in main class?

For that class it has code that allow us to do XCLASS. And I have 
configure follow XCLASS too. but it doesn't work for me.

Please give me some hints. if it works, is any configuration need?

I appreciate your hints.

Thank you,

Best Regard,