Hmm...I'm not familiar with this particular type of bus but the basics should be the same so here are my questions:
- are by any chance passengers getting on although the bus is not showing any destination?
- sure you selected the correct .hof file?
Had this issue with some other coach a while back (don't remember which now). Turned out I overlooked that the destination displays where not "generated" by a script but had to be created manually in paint.net (that's the software I use but there are lots of others out there) and saved in .bmp format. Maybe that's the case with the MAZ 251, too? The saved destination displays then need to be saved in \vehicles\Anzeigen\
YourNameOfBusHere
Just have a look and check if there maybe is a folder within the "Anzeigen" one that's named something like MAZ...
If yes, then it's the case that I described above and you have to create your own displays in order for the bus to show a destination
Hope this helps. If not, sorry, I tried my best
Derek