Question Why does my monitor say "No Signal"/"Cable Not Connected" when using a DisplayPort to DVI adapter?

[webberjo]

OS: Windows 10 Home (x64)
GPU: GTX 1660 Ti (has three DisplayPort 1.4 ports)
Monitor: Acer SA270 (has a single DVI-D Dual Link port)
Adapter: Topwin DP to DVI Male to Female Adapter Cable (male DP to female DVI-I Dual Link)
DVI Cables: DVI-D Single Link/DVI-D Dual Link

When using a DVI-D Single Link cable, my monitor says "No Signal".
When using a DVI-D Dual Link cable, my monitor says "Cable Not Connected".

I've tried restarting my computer and disconnecting and reconnecting my monitor's power cable.
All cables are plugged in tight and my monitor is set to DVI input.
The company I bought the adapter from thinks my computer is not compatible with the adapter, but I think the adapter is defective.

 

[Glenwing]

Most likely a bad adapter.

The company I bought the adapter from thinks my computer is not compatible with the adapter

That's nonsense unless the adapter is compatible with nothing.