sql error on script execution. try deleting repository before creating repository I want to migrate my mysql databse to oracle.
I have followed the migration demo from this url http://www.oracle.com/technetwork/database/migration/connect-step-mysql-1946352.html

but I got this message when try to associate migration repository 

sql error on script execution. try deleting repository before creating repository

I am using 
Oracle Sql Developer v 4.1.1.19Oracle express edition 11g releas 2

see the picture bellow what I have tried step by step

step1: Creating a user named migration_repo



step 2: Creating connection named migration_repo using migration_repo user


step3: try to associate migration repository
 

step4: executing the command


but after few seconds I got this error message.


Now. how can I solve this? what I have done wrong?
It seems that the video tutorial missed a grant, the correct command is the following:

GRANT 
    CONNECT, 
    RESOURCE, 
    CREATE SESSION, 
    CREATE VIEW, 
    CREATE MATERIALIZED VIEW 
TO migration_repo 
IDENTIFIED BY migration_repo;


The database must also have the USERS tablespace.
I found the previous information in this thread.