I have a 9477 that I'd like to use to enable a VFD which is configurable as NPN or PNP:

I understand that using the PNP config isn't possible without a relay or more EE than I am familiar with.
If it were a mechanical relay (or just a wire), in the NPN config, pulling DI1 to GND (pin 5) works fine, but when I use the 9477 it doesn't work, likely because it needs some current? I'm not exactly sure, any insight?