Can msfencode encode myself backdoor?

When I'm trying to encodemyself backdoor "Server.exe"(Not metasploit's payload),but it hang:

root@bt:/pentest/exploits/framework3# ./msfencode -i /root/Server.exe -c 1 -t exe -e x86/shikata_ga_nai -o sen.exe
[*] exec:./msfencode -i /root/Server.exe -c 1 -t exe -e x86/shikata_ga_nai -o sen.exe

----hang

What will you suggest me to do?? Where is the problem?Thanks a lot



PS
- BT 4 R2 , msf 3.7
- File is generated in windows,normal
- File size is 750 kB

msfencode accepts only raw file format not exe's so you will get an error message " .text section is too small " ... I was wondering if there is any way to convert exe to raw then encoding it and putting it back to an exe .... Sorry for the late reply ,only now i joined this forum ....

First off, I'd upgrade to the latest version of BackTrack & the Metasploit Framework. I think your best option is use msfpayload, in combination with msfencode. For example, "msfpayload [your payload] | msfencode -e [your encoder] > [your target exe filename]". Drop the exe on your target box, then start up a multi-handler in MSF that matches the payload in the exe. Whenever the exe is run on the target box, you've got your back-door.

You should try checking in with the metasploit support team they should be able to answer your question.