在编译tinyos 时出现问题，该怎么解决
/bin/sh: 1: tos-ident-flags: not found
mkdir -p simbuild/micaz
placing object files in simbuild/micaz
writing XML schema to app.xml
compiling BlinkAppC to object file sim.o
ncc -c -shared -fPIC -o simbuild/micaz/sim.o -g -O0 -tossim -fnesc-nido-tosnodes=1000 -fnesc-simulate -fnesc-nido-motenumber=sim_node() -fnesc-gcc=gcc -Wall -Wshadow -Wnesc-all -target=micaz -fnesc-cfile=simbuild/micaz/app.c -board=micasb -DDEFINED_TOS_AM_GROUP=0x22 --param max-inline-insns-single=100000 -Wno-nesc-data-race BlinkAppC.nc -fnesc-dump=components -fnesc-dump=variables -fnesc-dump=constants -fnesc-dump=typedefs -fnesc-dump=interfacedefs -fnesc-dump=tags -fnesc-dumpfile=app.xml
make: ncc: Command not found
/home/zhr/Documents/tinyos-release-tinyos-2_1_2/support/make/sim.extra:66: recipe for target 'sim-exe' failed
make: *** [sim-exe] Error 127
