awk system() command not working

I am using Sun Solaris 5.8

I am trying to run a system command such as ls and echo inside awk, but when I run the following code system echo is not displayed.

bash-2.03$ ls | awk 'BEGIN {
          print "first print"
          system("echo system echo")
          print "second print"
     }'

first print
second print

Please help

use 'nawk' instead of 'awk'