Creating an online development area

I have an existing wordpress site at sich.co.uk. I wish to change the theme to 2011 which is going to be a big change so I want to set up a development site. I have copied the old directory sich.co.uk/wordpress to sich.co.uk/wp.

I have copied all the tables from wp_* to dev_* in the database.
I have changed the $table_prefix = ‘dev_’; in the wp/wp-config.php file.
I have changed the siteurl in the dev_options table to http://www.sich.co.uk/wp

However when I try to log in at http://www.sich.co.uk/wp/wp-admin I get the error message

You do not have sufficient permissions to access this page.

I am obviously missing something any help would be appreciated.

Thanks in advance

Paul Howard