Rails 3 Application - Problem keeping integer in column with int (11) data type

I have a MySQL table structure:

+------------+----------+------+-----+---------+----------------+
| Field      | Type     | Null | Key | Default | Extra          |
+------------+----------+------+-----+---------+----------------+
| id         | int(11)  | NO   | PRI | NULL    | auto_increment |
| reg        | int(11)  | NO   |     | NULL    |                |
| descr      | text     | YES  |     | NULL    |                |
| created_at | datetime | YES  |     | NULL    |                |
| updated_at | datetime | YES  |     | NULL    |                |
+------------+----------+------+-----+---------+----------------+

And so I save the data in my database:

 @saving = Table.new(:reg => 1234, :descr => params[:descr]).save

And my problem is I don’t know how this is possible, but this query does not save the number in the column "reg". I get this error

Mysql2::Error: Column 'reg' cannot be null: INSERT INTOname_of_table (updated_at ,DESCR ,p ,created_at) VALUES ('2011-06-06 20:40:43', 'description of man', NULL, '2011-06-06 20:40:43')

I worked a lot with PHP and the MySQL database, but I never got this error ... Where is the problem?