Thank you Antonio,you make great help here.
Thats exactly my problem you solved.My new OS is windows pro 64 bits(instead my old 32 bits).
i have the 2 system folders: c:\windows\sysWow64 and c:\windows\system32.the "native" becomes then syswow64.
snippingtool.exe is located in c:\windows\system32 only.even copied in syswow64, it dont work !

I am surprised that MS makes this similar mistake and invents the "sysnative" new concept.
its preferable it makes some internal function sweetching between the folder syswow64 and system32 on need.
If giving even the fullpath the command execution does not work ! must add "sysnative" !
run/n c:\windows\system32\snippingTool.exe or similar (shellexecute,..) dont work.
run/n snippingtool also does not work.the "set path.." vfp concept seems to dont be understand by MS!

if having a win64 OS:
- if the file is located in syswow64 : all is ok .it runs normal
- if the file is located in system32 :that dont work in execution,must replace "system32" by "sysnative".

try
run/n snippingtool
catch
run/n c:\windows\sysnative\snippingtool
endtry

this is hard for whose have already built applications ! must re maintain all codes...MS makes the life more difficult.

i found this relevant link for this problem:
https://msdn.microsoft.com/en-us/library/windows/desktop/aa384187(v=vs.85).aspx