With a lowercase c in crunch, I have been able to successfully run the command you have here without issue.
This is on a new Kali-Rolling 2016.1 with crunch version 3.6-2
Code:
root@kali:~/Desktop# dpkg -l | grep crunch
ii crunch 3.6-2 i386 tool for creating wordlist
root@kali:~/Desktop# ls -lah
total 8.0K
drwxr-xr-x 2 root root 4.0K Apr 20 13:56 .
drwxr-xr-x 23 root root 4.0K Apr 17 11:57 ..
root@kali:~/Desktop# crunch 4 4 abcdefghijklmnopqrstuvwxyz -o /root/Desktop/wordlist.txt
Crunch will now generate the following amount of data: 2284880 bytes
2 MB
0 GB
0 TB
0 PB
Crunch will now generate the following number of lines: 456976
crunch: 100% completed generating output
root@kali:~/Desktop# ls -lah
total 2.2M
drwxr-xr-x 2 root root 4.0K Apr 20 13:56 .
drwxr-xr-x 23 root root 4.0K Apr 17 11:57 ..
-rw-r--r-- 1 root root 2.2M Apr 20 13:56 wordlist.txt
root@kali:~/Desktop# head wordlist.txt
aaaa
aaab
aaac
aaad
aaae
aaaf
aaag
aaah
aaai
aaaj
root@kali:~/Desktop#