If you are the adding the Printable -pricelist plugin to new zc158a installation with a clean zc158a database when checking the database content use the same sql query
Code:
SELECT * FROM configuration WHERE configuration_key LIKE 'PL_%';
If you have used a table name prefix like "zen_" you will change the table name in the query to suit eg
Code:
SELECT * FROM `zen_configuration`
If you get errors post them here.

Always apply and test changes in a test environment first.