All AudioBox VSL series
Make sure that the fader for the FX buses is raised and that the FX preset you have loaded on that bus has parameter settings high enough to create the desired effect. Also make sure that the channels you want to have reverb or delay on them have send levels raised for the correct effect bus.
AudioBox 44VSL and AudioBox 1818VSL only
The AudioBox 44VSL and AudioBox 1818VSL give you the option to patch or unpatch the effects buses to each output pair. Make sure that the FXA and FXB patch buttons on the output bus are enabled.
Please contact PreSonus Technical Support by creating a Support Ticket at My.PreSonus.com for further assistance.