Ok, then you need to add a condition to ultralcd_st7920_u8glib_rrd.h
locate line 56 and make sure it reads:

#elif MB(MINIRAMBO) || MB(EINSY_RAMBO)
Since my board is an MKS Gen (v1.4), I added it to the end of this line, so it reads:

#elif MB(MINIRAMBO) || MB(EINSY_RAMBO) || MB(MKS_GEN_13)