I can no longer take or post current photos. Maybe my 1997 solution for a effective shelf connection will provide one method.
Look right under the drivers of Mikado 4815 (above) and you will see two small machine screws holding a short two-hole mending plate--look carefully and you can also see the plate . There is also a plate lying down in the channel on top which does not interfere with the drivers.
I gave up on using the connectors and went to Lowe's for the little mending plates and screws. I simply drilled holes in the shelf to match the mending plate holes and made the connection . I didn't need a plate at the rear of the joint since the wall connection ensured alignment. Makes a secure perfect alignment.
On an uneven studded drywall I used fender washers (Lowe's) to shim the shelf in wall "valleys" to enable tightening screws which avoided hump and a wavy shelf.