How to execute prepared statements inside stored procedures with user vars?

I am trying to write a stored procedure to create a temporary table with variable columns created based on the linked data of 2 tables. I get the variable fields to be added to the temp table using a query in cursor and I try to add the fields to the temp table using this loop:

OPEN acc_data_fields;

PREPARE stmt FROM 'ALTER TABLE `test`.`tmp_123` ADD COLUMN `?` VARCHAR(255) AFTER `?`';

add_tagheads: LOOP

 FETCH acc_data_fields INTO field_tmp;

IF exit_flag = 1 THEN

    LEAVE add_tagheads;

 END IF;

 EXECUTE stmt USING @field_tmp, @add_after;

 SET @add_after = @field_tmp;
END LOOP add_tagheads;
DEALLOCATE PREPARE stmt;
CLOSE acc_data_fields;

The Stored proc fails at EXECUTE with the error

Sql Error 1210 Incorrect Arguments to EXECUTE

I read through similar posts but not able to figure out what's wrong. The DB is Mysql 5.1. Any suggestions guys?