MiniRambo with radds display

I’ve been able to lay my hands on a MiniRambo for free, from another project, I’m thinking of building another MPCNC with this. I got the electronics togehter, flashed the firmware, included the libs etc, hooked it up to printrun and all steppers move, great.
Expect I can’t get that awfull 4x20 RADDS display to work. So I figured it’s toast since I uncommented the line in the config

// Original RADDS LCD Display+Encoder+SDCardReader
// http://doku.radds.org/dokumentation/lcd-display/
//
#define RADDS_DISPLAY

And flashed that … No es Bueuno.

But then just to rule it out and not binning a working part I flashed the Prusa mk2s HEX binary. Lo and behold, the display works, the encoder too, all fine.

So what am I missing?

Thx!