yeah, the program automatically closes regardless of if it errors or not, so you cant see the error message that way.
open the console window and run it manually (navigate to the folder with the exe and the txt file and just type "ggsound.exe txtfile.txt" without the quotes to run it)
generally when you dont get an .asm file, the converter produces a "keyerror" indicating that something is wrong somewhere.
the keyerrors refer to your instruments.
see this post: http://nesmakers.com/viewtopic.php?f=39&t=1919&start=10#p15403
for details on how to understand where your error comes from.