PostgreSQL Insert error on a not null Value

I'm getting a weird error when trying to execute an insert query on a PostgreSQL database. I'm executing the following query:

insert into "shopping_carts" 
    (
    "application_version", "charges", "device_id", "device_type", "id", "new_client",
    "os_version", "platform_name", "resolution", "shopping_cart_date",
    "shopping_cart_date_day", "shopping_cart_date_day_of_week",
    "shopping_cart_date_day_of_year", "shopping_cart_date_hour",
    "shopping_cart_date_minute", "shopping_cart_date_month",
    "shopping_cart_date_numeric", "shopping_cart_date_quarter", 
    "shopping_cart_date_quarter_name", "shopping_cart_date_second", 
    "shopping_cart_date_week_of_year", "shopping_cart_date_year", "status", 
    "store_id", "store_name", "tip", "total_after_discounts", "total_discount", 
    "total_items", "user_gender", "user_id", "whim_has_photo", "whim_what", 
    "whim_where"
    ) 
values 
    (
    2.0, 0.0, '105755B41135E2A6F5C09089EE776BA179A4DD290E27B6DC11AFC94534572BD7', 
    'smartphone', 'QWFISFJ23434', true, 'Ubuntu 15.10', 'ios', '1920x1080', 
    '2016-06-20 18:42:15', 20, 1, 171, 18, 42, 6, 1466448135, 2, 'Second Quarter', 
    15, 25, 2016, 'PROGRESS', 15, 'BOG F. Centro Andino', 0, 0, 0, 0, 'M', 32, 
    TRUE, 'Lechona', 'Lechoneria de la esquina'
    )

The error is:

Kernel error: ERROR: null value in column "tip" violates not-null constraint

DETAIL: Failing row contains (QWFISFJ23434, 0, 0, 0, PROGRESS, null, null, 0, 15, BOG F. Centro Andino, null, null, null, 32, M, Ubuntu 15.10, 1920x1080, 2.0, ios, 105755B41135E2A6F5C09089EE776BA179A4DD290E27B6DC11AFC94534572BD7, smartphone, 2016-06-20 18:42:15, 1466448135, 2016, 6, 20, 2, Second Quarter, 171, 1, 25, 18, 42, 15, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, t, null, null, null, null, null, null).

I'm clearly sending a value for the "tip" column, so I don't understand why I'm getting this error.

Also, there is some additional information that maybe useful:

1. In the error detail, there is a weird "t".
2. The shopping_carts table has more column but they are all nullable.
3. In the DB exists 3 tables which inherit from the shopping_carts table, and have insert rules in the shopping_carts table.
4. I'm using Laravel migrations to create the DB

Thank you for any help you can give me.

Found the solution.

I had an insert rule on the shopping_cart child tables. The problem was that I added the "tip" column after the rules where defined.

I had to execute the rules queries again to update them. That solved the problem.