what does this error mean?

I am writing some data from my java file to an excel file, and at run time I get this error:jxl.write.biff.JxlWriteException: Attempt to modify a referenced formatwhat does this error mean? What should I do to get lost of it?
[246 byte] By [aditma] at [2007-11-27 0:35:51]
# 1
That is a third-party exception that is not part of the Java API. There is no way we can know what it is or what caused it.We can suggest however that you find documentation for that particular Java class to gain more insight into where the problem might be.
maple_shafta at 2007-7-11 22:44:46 > top of Java-index,Java Essentials,Java Programming...
# 2
thank you
aditma at 2007-7-11 22:44:46 > top of Java-index,Java Essentials,Java Programming...