Ok, i understand my mistake, it was $fieldlist1 = "[cb_list_01]"; with the double quotes.
Now i have a second question : I have 3 list fields. The first need to populate the second and the second populate the third.
If i had already choose a value in the first and second (so the third is populated too) and now i modify the first, The second is modified too but not the third. The "change" event seems not to be fired when the second field is modified by the first so the third one is not modified... How to to this ?