late 2012 mac mini to dell 2416 thunderbolt 2560x1440

Has anyone else got a late 2012 mac mini working at full resolution to a dell 2416D?

I can connect via hdmi, but that gives max 1920x1080

I have bought a mini dp to DisplayPort cable, but when I try connecting with this, the monitor stays blank and says no signal.

I have connected the monitor fine to a windows pc using DisplayPort -> DisplayPort cable @ full 2560x1440 resolution.

Anything I can do to the mac mini or the monitor to make them recognize each other?