Kate, Quanta do not keep char encoding setting

Hi,
I have a strange problem, I am running 11.1 64 with kde 3.5. Char encoding is set to utf8 by default on the system, and everywhere. Normally (it happened that way one week ago) when I open an text file with iso-8859-1 encoding, kate, quanta opened it correctly with the accurate encoding. Now, I really don not know why, when I try to open a file with kate or quanta, the char encoding remains utf-8 and it is impossible to change, when I try manually to change the setting, the editor display flashes and returns to utf-8… On the other hand, if I open the same file with Kate4 or gedit, everything is ok.

Any idea of what is happening to me ?