wow, I almost forgot that old tool.
the usage is right (port is 27015 by default if you don't specify it).
that message means that the server didn't reply to the "infostring" query sent by the tool for being sure that the server is active.
you need to modify the source or you can substituite the following bytes in hlspfed.exe:
Code:
Offset original patch
-------------------------
00001092 89 31
00001093 C3 DB
anyway I no longer support that old stuff.