Accent Mark

[Daniele]

Hy,
I'm italian. In italian language we use accent mark. I'm using a
firebird DB (charset iso8859_1).
When I insert or update a record with accent mark like "ò" obtains
this error:
FireRuby::FireRubyException: Error executing SQL statement.
arithmetic exception, numeric overflow, or string truncation
Cannot transliterate character between character sets
Arithmetic overflow or division by zero has occurred.
SQL Code = -802
Firebird Code = 335544321
: UPDATE table SET "FIELD_NAME" = 'test?' WHERE id = 4.0

Can you help me, please?

Daniele