I just had this same issue and got past it. It was an issue with the shellcode length. Needed to be exactly 410 bytes.
I used the following sploit: Microsoft Windows - 'NetAPI32.dll' Code Execution (Python) (MS08-067) - Windows remote Exploit
I generated my shellcode with msfvenom and added NOP bytes (\x90) to the front of the shellcode to reach exactly 410 bytes.
To help with accuracy, I added a line after the shellcode to print the shellcode byte count in my local copy of the script (Python v3.x):
print(len(shellcode))
Took me way too long to figure that out and tried too many things leading up to that! I hope that helps!