callweaver - error

\
                if test ! -d "${install_dir}"; \
                then \
                        mkdir -p ${install_dir}; \
                        chmod 0750 ${install_dir}; \
                fi; \
                if test -z ""; \
                then \
                        chown callweaver:callweaver ${install_dir}; \
                fi; \
        done
chown: `callweaver:callweaver': invalid user
chown: `callweaver:callweaver': invalid user
chown: `callweaver:callweaver': invalid user
chown: `callweaver:callweaver': invalid user
chown: `callweaver:callweaver': invalid user
chown: `callweaver:callweaver': invalid user
chown: `callweaver:callweaver': invalid user
chown: `callweaver:callweaver': invalid user
chown: `callweaver:callweaver': invalid user
chown: `callweaver:callweaver': invalid user
chown: `callweaver:callweaver': invalid user
chown: `callweaver:callweaver': invalid user
chown: `callweaver:callweaver': invalid user
chown: `callweaver:callweaver': invalid user
chown: `callweaver:callweaver': invalid user
make[3]: *** [install-data-hook] Error 1
make[3]: Leaving directory `/root/callweaver'
make[2]: *** [install-data-am] Error 2
make[2]: Leaving directory `/root/callweaver'
make[1]: *** [install-am] Error 2
make[1]: Leaving directory `/root/callweaver'
make: *** [install-recursive] Error 1
root@dell:~/callweaver#