[gentoo-user] php CURRENT_TIMESTAMP vs NOW()

[Joseph]

I'm not a PHP programmer but I'll try to explain my problem.
I've create table in my php database:
DROP TABLE IF EXISTS visual_verify_code;
CREATE TABLE visual_verify_code (
  oscsid varchar(32) NOT NULL,
  code varchar(6) NOT NULL,
  dt TIMESTAMP(12) NOT NULL DEFAULT NOW(),
  PRIMARY KEY (oscsid)
);

It worked OK, after few days I backup my database and try to restore it, but it keeps 
complaining on the "dt":
ERROR 1067 (42000) at line 38009: Invalid default value for 'dt'

so the database is dropped but never restored. The backup data base contain:

create table visual_verify_code (
  oscsid varchar(32) not null ,
  code varchar(6) not null ,
  dt timestamp default 'CURRENT_TIMESTAMP' not null ,
  PRIMARY KEY (oscsid)
);

so the difference is:

 dt TIMESTAMP(12) NOT NULL DEFAULT NOW(),
vs
 dt timestamp default 'CURRENT_TIMESTAMP' not null ,

If I change in backup database the line to: "dt TIMESTAMP(12) NOT NULL DEFAULT 
NOW(),"
I can restore it without problems.  

Why is it doing it?  
In "dt" table structure the "default" has option:
- None
- As Defined:
- NULL
- CURRENT_TIMESTAMP

If I change setting from "CURRENT_TIMESTAMP" to any of the above will it help restore it correctly? 

--
Joseph