Good chance that IR remote will not work those DVRs anymore. I've seen this happen with cheap CCTV products before; where the DVRs did a firmware update and it killed the IR remote functionality (i.e. they took that functionality away with the firmware update).
Not sure if this is the case with your systems, but it's a good bet.
Looking over their website, it doesn't appear they offer much in the way of support. Or anyway to manual update firmware or reinstall older firmware.