Import CSV Strenge problem with Categories

Hi,

i notice a streng behavior after importing data from csv .
(you helped me once with the csvform.php maybe there is any kind of error?--> joomdonation.com/forum/os-property/46200...e-energy-rating.html )

The Problem:
1. i have 2 categories : for sale , for rent
2. I made 2 import forms in joomla backend: for sale, for rent.
the only one difference between them ist the category. Ive seen inside of the new csvform.php , its searching for category name , not id, so in my csv file for import in the column category ist set: for sale or for rent, depending the form.

3. now when I import properties i get no errors during import of csv & photos, but then:

A: All properties are in both categories....?!?
B: In the database in the column category_id every property has NULL
C: even if I change the category_id to the correct one (in my case 12-for sale, 13-for rent), nothing changes in Joomla Backend, still both categories
even if I add new property , the category_id stays NULL ---> ist that OK? what if I want bulk change the category for f.ex. 300 properties?

Thanx in advance:)