Note the bright green plates 1x2 in the rendering.

These need to be replaced with plates 1x2 HALF plate thick.

To get this, cut 4 red & 4 yellow brackets 44728.dat with a sharp knive.
Reuse all the red pieces, and the 4 yellow 1x2 half thick plates.
the remaining yellow brackets (like the 99781.dat) can be put away.

Take care for your fingers while cutting!

success.