Rails - Jul 2006 - Error in new record using Fireruby

The Action Controler List worked, but if i add one new record, i''m view
the
message bellow 

" 
FireRuby::FireRubyException: Error preparing a SQL statement. 
Dynamic SQL Error 
SQL error code = -842 
Precision must be from 1 to 18 
Wrong numeric type 

SQL Code = -842 
Firebird Code = 335544569 
: SELECT CAST(0 AS DECIMAL(0,0)) FROM RDB$DATABASE 
" 

I''m apreciate any help, is are welcome :-) 

PS. Sorry may bad english 

i''m using 
My development enviroment 
Ruby version               1.8.4 (i386-mswin32) 
RubyGems version           0.9.0 
Rails version              1.1.4 
Active Record version      1.14.3 
Action Pack version        1.12.3 
Action Web Service version 1.1.4 
Action Mailer version	   1.2.3 
Active Support version	   1.3.1 
Application root	   D:/Site/rails/membros 
Environment	           development 
Database adapter	   firebird 

Joseh-Henrique 
Goiania, GO 
Brazil