Service - Forum - Taxonomy

I set the SPXXL-Category by custom programming as described in the FAQ ( http://www.sharepartxxl.com/products/taxonomy/Lists/FAQs/DispForm.aspx?ID=24 ). This works fine, but I notice a very interesting effect: The SPXXL-Category is set correctly through my custom code depending on other columns, I can see it in my Document Library. But in the Categories List the corresponding document doesn't appear. So I go ahead and change the document properties and again depending on other columns the SPXXL-Category is changed, too, through my custom code. Now the document appears in the Categories List, but surprisingly under the category it should have had before and not under the category currently set in the Document Library. Again I change the properties and, voilá, the SPXXL-Category in the Document Library is set correctly, but in the Categories List the document now shows under the Category it was set to during the first modification. So it seems the listing always is one step behind the current value. Has anyone else experienced this behavior? Does it relate to my custom code? How does the Categories List get its information and when? If anyone wants to inspect my code just tell me at heile (at) web (dot) de. Thanks in advance for any hint. Stefan :-)