Ubuntu – DKMS build failing without meaningful error

I'm trying to enable a kernel module I've got from a device vendor to work with DKMS. I can successfully build the module and manually install and enable it. But when using DKMS a get an error that doesn't help me in any way:

$ sudo dkms build -m biokernbase -v 3.1.2.1

Kernel preparation unnecessary for this kernel.  Skipping...

Building module:
cleaning build area....
make KERNELRELEASE=3.13.0-123-generic all KVERSION=3.13.0-123-generic DKMS=y
....
.ko failed for: 3.13.0-123-generic (x86_64)
Consult the make.log in the build directory
/var/lib/dkms/biokernbase/3.1.2.1/build/ for more information.

make.log

DKMS make.log for biokernbase-3.1.2.1 for kernel 3.13.0-123-generic (x86_64)
Wed Dec 13 17:22:51 CET 2017
make -C /lib/modules/3.13.0-123-generic/build M=/var/lib/dkms/biokernbase/3.1.2.1/build modules
make[1]: Entering directory `/usr/src/linux-headers-3.13.0-123-generic'
  CC [M]  /var/lib/dkms/biokernbase/3.1.2.1/build/main.o
  CC [M]  /var/lib/dkms/biokernbase/3.1.2.1/build/event.o
  CC [M]  /var/lib/dkms/biokernbase/3.1.2.1/build/usbreader.o
  CC [M]  /var/lib/dkms/biokernbase/3.1.2.1/build/memory.o
  CC [M]  /var/lib/dkms/biokernbase/3.1.2.1/build/misc.o
  CC [M]  /var/lib/dkms/biokernbase/3.1.2.1/build/isa.o
  LD [M]  /var/lib/dkms/biokernbase/3.1.2.1/build/biokernbase.o
  Building modules, stage 2.
  MODPOST 1 modules
  CC      /var/lib/dkms/biokernbase/3.1.2.1/build/biokernbase.mod.o
  LD [M]  /var/lib/dkms/biokernbase/3.1.2.1/build/biokernbase.ko
make[1]: Leaving directory `/usr/src/linux-headers-3.13.0-123-generic'

dkms.conf

PACKAGE_NAME="biokernbase"
PACKAGE_VERSION="3.1.2.1"
CLEAN="make clean DKMS=y"
MAKE[0]="make all KVERSION=$kernelver DKMS=y"
BUILT_MODULE_NAME[0]="biokernbase"
DEST_MODULE_LOCATION[0]="/kernel/drivers/misc"
AUTOINSTALL="yes"

Makefile

DRV_NAME := biokernbase
DRV_PATH := daqnavi
KVERSION := $(shell uname -r)
KDIR     := /lib/modules/$(KVERSION)/build
BASE_DIR := /usr/lib/daqnavi

obj-m := $(DRV_NAME).o
$(DRV_NAME)-objs := main.o event.o usbreader.o memory.o misc.o isa.o

EXTRA_CFLAGS += -I$(BASE_DIR)/include -I$(BASE_DIR)/include/hw -I$(BASE_DIR)/include/linux
SYMBOL_PATH = $(BASE_DIR)/modules

all:
    $(MAKE) -C $(KDIR) M=$(PWD) modules

clean:
    $(MAKE) -C $(KDIR) M=$(PWD) clean
    rm -f *.o *~ .depend .*.cmd *.ko *.mod.c .tmp_versions modules.order Module.symvers

Update 1: kernel compatibility

I'm currently on Ubuntu 14.04.5 LTS with kernel 3.13.0-123-generic.

The vendor's documentation states compatibility with Ubuntu 12.04/14.04/15.10, kernel version 3.2/3.13/4.2.

When I manually copy the biokernbase.ko built by dkms to /lib/modules/3.13.0-123-generic/kernel/drivers/misc/, the kernel module seems to be loaded successfully:

$ sudo modprobe biokernbase; echo $?
0

Any ideas or hints are highly appreciated.