Mod-plugin-builder calf-labs

Hi,
running mod-plugin-builder on a Ubuntu Server VM. The most plugins can made without problems.

But ./build modduox calf-labs and ./build modduox calf gives me the error:

/bin/bash: …/src/calfmakerdf: cannot execute binary file: Exec format error
make[6]: *** [Makefile:642: install-data-hook] Error 126
make[5]: *** [Makefile:574: install-data-am] Error 2
make[4]: *** [Makefile:528: install-am] Error 2
make[3]: *** [Makefile:370: install-recursive] Error 1
make[2]: *** [Makefile:565: install-recursive] Error 1
make[1]: *** [package/pkg-generic.mk:279: /home/modp/mod-workdir/modduox/build/calf-labs-0.0.60/.stamp_target_installed] Error 2
make: *** [Makefile:36: _all] Error 2

Whats going wrong?