Thanks! It solved!

Should I inform the template maker?

Another question: think this template is not so popular since it was launched from Aug 06 until now no body was noticed about this problem...

I am recently using the following versions:

Serendipity v1.1.2
Chocolate Fudge Theme
Markup: Serendipity
Markup: Emoticate
Browser Compatibility
Spamblock
Statistics
Spartacus
Tagging of entries
Typeset/Extended Buttons for non-WYSIWYG editors
Show last modification date
Markup ...