Firmware compiling

[PavelBab]

Hi,
I need additional modules for apcupsd (usbhid,..).
Due to this I need compile the firmware.
I installed Debian linux into VirtualBox and executed all steps according to a Merlin manual.
I recieved following errors during comilation process:

make[7]: *** No rule to make target '../../include/openssl/rc4.h', needed by 'eng_openssl.o'. Stop.
make[7]: Leaving directory '/home/pavel/asuswrt-merlin/release/src/router/openssl/crypto/engine'
Makefile:88: recipe for target 'subdirs' failed
make[6]: *** [subdirs] Error 1
make[6]: Leaving directory '/home/pavel/asuswrt-merlin/release/src/router/openssl/crypto'
Makefile:288: recipe for target 'build_crypto' failed
make[5]: *** [build_crypto] Error 1
make[5]: Leaving directory '/home/pavel/asuswrt-merlin/release/src/router/openssl'
Makefile:1620: recipe for target 'openssl' failed
make[4]: *** [openssl] Error 2
make[4]: Leaving directory '/home/pavel/asuswrt-merlin/release/src/router'
Makefile:861: recipe for target 'obj_prelibs' failed
make[3]: *** [obj_prelibs] Error 2
make[3]: Leaving directory '/home/pavel/asuswrt-merlin/release/src/router'
Makefile:202: recipe for target 'all' failed
make[2]: *** [all] Error 2
make[2]: Leaving directory '/home/pavel/asuswrt-merlin/release/src-rt-6.x.4708'
Makefile:2826: recipe for target 'bin' failed
make[1]: *** [bin] Error 2
Make[1]: Leaving directory '/home/pavel/asuswrt-merlin/release/src-rt-6.x.4708'
Makefile:2896: recipe for target 'rt-ac68u' failed
make: *** [rt-ac68u] Error 2

Can anybody help me where is problem and how to solve it?

Thank you.