xslt extensions error : 'Call to extension function failed'

I am trying to use xslt java extensions and am having problems when I write
my own custom classes and try to use them. When I use the "xmlns:java"
namespace the code runs fine.  
The error I get when using my custom class is : "Call to extension function
failed: com.example.DateFormatter". The problem is the error doesnt give out
much information. Does anyone know what the possible cause'(s) of this error
are. Btw the code happens to run on an appserver. Thanks in advance for all
the help.
 
Amit

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