Issues with measuring multiple switch inputs via single DAC in R-2R resistor configuration

Working on a project trying to measure multiple switch inputs via a single DAC in an R-2R resistor configuration. Took me a while to realize that the inputs needed to be HIGH or LOW, not HIGH or OFF. What also threw me off though was that each side of the breadboard's power/ground rails need to be jumpered together in the middle. That took me a while to figure out too. Guess you shouldn't assume anything when working on hardware!