HELP - Error: Libxml returned a null pointer

Hi guys;

I'm working with kannel wap gateway and it had been working well until this 
week (on SUSE Linux 8.0 and  Proliant ML370 Hardware). 
When users try to get a wml page the next error is showed by kannel:
ERROR: Libxml returned a null pointer
All wml compilation failed

This wml page has a code to query a database. Now, I have more than one wml 
page with the same error at the same site and I can change the wml code because 
is from a content provider.

Does anyone had this error? How can I fixed it?. Please, if this error doesn't 
have solution I will have to change kannel by other wap gateway.

Thanks for your help.