Thanks,
This error happen on Filter, theme, tooltips, or doing nothing (if i use this class to make a layer, it will never appear on the preview screen and the log fill up with this error).
I Tried to use basic table, filtering String Or Numeric is the same.
And no, unfortunately i can't label the SDF because data in the database (for tooltips) can be changed by the user.
My OS is French Windows 2003, Oracle use the AMERICAN_AMERICA NLS.