ERROR 1064(42000) occuring in trigger while concatenating the value

I want to define a trigger which will concat a numeric value with some characters and followed this Question How to make MySQL table primary key auto increment with some prefix as help but I am getting the error 1064.

mysql> desc autoid.
+-------+---------+------+-----+---------+----------------+
| Field | Type    | Null | Key | Default | Extra          |
+-------+---------+------+-----+---------+----------------+
| ID    | int(10) | NO   | PRI | NULL    | auto_increment |
+-------+---------+------+-----+---------+----------------+

This is my table for the auto increment ID

mysql> desc company_warehouse.
+----------------+---------------+------+-----+---------+-------+
| Field          | Type          | Null | Key | Default | Extra |
+----------------+---------------+------+-----+---------+-------+
| ID             | varchar(12)   | NO   | PRI |         |       |
| PRODUCT_NAME   | varchar(30)   | YES  |     | NULL    |       |
| QTY            | int(6)        | YES  |     | NULL    |       |
| PRICE_PER_UNIT | decimal(10,2) | YES  |     | NULL    |       |
+----------------+---------------+------+-----+---------+-------+

This is the main table where the ID will be stored as 'p1','p2',...

mysql> CREATE TRIGGER tg_company_warehouse
    -> BEFORE INSERT ON company_warehouse
    -> FOR EACH ROW
    -> BEGIN
    -> INSERT INTO autoid VALUES(NULL);
    -> SET NEW.ID = CONCAT('P',LPAD(LAST_INSERT_ID(),1,''));
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 6
    ->

This is where I am getting the error while defining the trigger. I had changed my default Delimiter also to '.'