This error indicates that the logged in user does not have sufficient permissions to access the Accounting Interface. To grant permissions to the accounting link, click on Administration >  Manage Users , 

then select the required user from the user list. Once the user is highlighted, click on the key symbol to view the users permissions. From the permissions window, highlight the "Accounting Link" option, and ensure that all the tick boxes for the accounting interface are ticked.

Log out of Legrand and log back in, to enable the new user permissions to propagate.