So i'm testing an exploit on my deticated server, and a calc.exe proof of concept works fine but when i change the shellcode to anything else it doesnt work,( by anything, i mean "create admin user" ) I tried every encoder on the metasploit shellcode generator. any tips on how to make this exploit work on a win server 2003? i tried it locally on a virtual machine (same OS) and it worked there so im puzzled, something with packets going through internet screwing it up?

all i can thing of is diferent build (of the OS)? but the shellcode does crash the service so its hitting some code