Problem with foreign key constraint

I am getting error #1005 - Can't create table (errno: 150).

I have been through the checklist of:

• both tables are InnoDB
• the columns are the same type (INT)
• attributes are the same (UNSIGNED NOT NULL)
• the collation开发者_如何学C is the same
• I have tried with indexes on the foreign keys, it still doesn't work (and they shouldn't be needed for MySQL 5)

The problem was with my syntax. Instead of

REFERENCES `table`.`col`

it should be

REFERENCES `table` (`col`)

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