Using DennyTX's Landing Aim addon. Instead of a crosshair, all I see is a 'flat' square box.

[iFlyAllTheTime]

I'm using 1.2.2.1 of the mod, which is the correct version for my KSP 1.2.2 save (I know. I'll occasionally play 1.9,  but I'm deep into a save game on 1.2.2 and never got around to migrating it over to the newer ones).

I know it's an old and probably obsolete addon at this point. But I'd appreciate if someone could point me in a direction to be able to troubleshoot this.

Here are the contents of the mod folder:

 

[sturmhauke]

The forum thread is over here:

DennyTX hasn't been active in over a year, and the mod was updated to 1.3.1 at some point. Beyond that, I don't know, sorry. If you do decide to update to a more recent version, you could try the Trajectories mod instead.