Reply to Ikea DJ Booth Problems !!

So I've had the Ikea DJ booth for less than a month now , but never finished it because I've had a problem I can't find the answer too

The CAPITA angled bracket won't go through the desk because the bottom of it is the same thickness as the desk , no way to tighten the bolt underneath it !

Anybody else have this problem , and how did you fix it !
Pictures would be greatly appreciated!

Thanks,
Swede