Since osCMax uses Admin access levels to control which users can access certain sections of the admin area if you need to add access to <a new file.php> within the ADMIN section you need to enable access to the file.
Open your Admin panel
Click on the Administrator Menu box
Click File Access in Menu box
Select the Catalog row in the central box
Click Store Files in right hand column
Select <a new file.php> from the drop down
Click Save
Open your Admin panel
Click on the Administrator Menu box
Click Member Groups
Click the groups button
Select the row of the group you want to edit
Click New Permission button
Untick / Tick the items you want to Hide / Show to this user group
Click save at the bottom of the page
You can not edit the Top Administrator permissions as they have access to all menu items by default to prevent you from locking yourself out!
Don't forget to go back and Set Admin Group Access