Simpropcompiler.exe when FSX not installed

I am trying to compile my XML files to SPB files with simpropcompiler in a PC in which FSX is NOT installed.
I've tried to copy propdefs symbols to a local folder, even use them from a shared netowrk (sharing FSX root folder, X:\propdefs\*.xml, for example). No matter what I do, I always get the following error:

Invalid symbol search path : "X:\propdefs\*.xml"
myfile.XML(0) : error 83600fb4 : Unable to load symbols

I have got simpropcompiler.exe and my *.xml files in my work folder.

I try to execute:

simpropcompiler 2spb -symbols X:\propdefs\*.xml myfile.XML myfile.spb
simpropcompiler 2spb -symbols X:\propdefs\*.xml -i X:\propdefs\*.xml myfile.XML myfile.spb

So, as if I compile it at my FSX PC, it does it successfully at first try... does anybody know what piece of FSX (registry entries, files, etc.) needs simpropcompiler.exe to compile properly?

Thanks a lot ;-)