[uCsimm] What's the problems with the serial program??

Hi everyone, I encountered a problem, I want to run a serial program which is used to read the console port of the uCsimm instead of using the agetty.c. The serial program can be run on my RedHat6.2 and the program can also be cross complied, but as long as I run it on the uCsimm, it has no respond. The serial program that I used is copied from the "HOW-TO" on-line document of my RedHat. Can someone tell me what is the problems? Or some of the commands cannot be run on the uCsimm?