Please help me. About the conversion from wbxml to xml

Dear Sir:
 I am very sorry for bothering you, but I have a question concerning the 
conversion from wbxml to xml which I can not solve.
 My question is :if I want to convert a wbxml file to xml file, is it so 
simple just to use the kxml wbxml tool to do the conversion? do I need to 
add some more information into the conversion file, some device information?
Currently I am using Nokia 6600 to do the testing, do I need to add some 
6600 device information into the programme?

Sometimes when I use the kxml wbxml conversion tool, the xml file can be 
converted into the corresponding wbxml file, but it can not be converted 
back.
Sometimes, one xml file can be converted,but after I changed something which 
is not important for conversion in the file , the file can 't be 
converted!!!!!!!!!
I am really exausted!!!
Please help me!!!
Thank you very much.
Wish your reply.

_________________________________________________________________
MSN 8 helps eliminate e-mail viruses. Get 2 months FREE*. 
http://join.msn.com/?page=features/virus