text highlighting problem

[JanK]

Hi !
 I've got some problems with text highlighting. I'am using some special 
library that handles text reduceing/canonization (used language is 
Polish). The reduced words has no flexion (which is usefull feature in 
the context of searching). The problem is when i try to perform text 
highlighting because the highlighting tags are not in a correct position 
(they are shifted), for example:
this is s<br>ome tex</br> t to highlight. The canonization library is 
integrated with analyzer in the following manner:
public final class MyAnalyzer extends Analyzer
{
  public TokenStream tokenStream(String fieldName, Reader reader)
 {
  MyCanonizer textCanonizer = new MyCanonizer();
  TokenStream ts = new 
StandardTokenizer(textCanonizer.peformCanonization(reader));
  return ts;
 }
}
Could anybody say why the highlights are shifted and/or how to solve the 
problem ?

Thanks,
JanK