ExecDos keeps "trapping"

I'm trying to start a console program (MakeCab.exe actually) in to background silently, and ExecDos seemed to suit well. But something is wrong as this code example keeps trapping all the time.

Please tell me what I'm doing wrong here (Far nor Makecab never starts):

!include "nsDialogs.nsh"



!AddPluginDir .



OutFile "test4.exe"



Page license

Page custom nsDialogs_Create nsDialogs_Leave

Page license



Var handle



Function nsDialogs_Create



	nsDialogs::Create /NOUNLOAD 1018

	Pop $0

	StrCmp $0 error 0 +2

	  Abort



	${NSD_CreateLabel} 10u 10u 100% 10u "Please, wait a minute while backup files are being compressed."

	Pop $0



	GetDlgItem $R1 $HWNDPARENT 1 ; disable NEXT button

	GetDlgItem $R2 $HWNDPARENT 2 ; disable CANCEL button

	GetDlgItem $R3 $HWNDPARENT 3 ; disable BACK button

	EnableWindow $R1 0

	EnableWindow $R2 0

	EnableWindow $R3 0



	ExecDos::exec /NOUNLOAD /ASYNC "C:\Program Files\FAR\Far.exe"

	Pop $handle # thread handle for wait



	${NSD_CreateTimer} Timer1 1000



	nsDialogs::Show



FunctionEnd



Function nsDialogs_Leave

FunctionEnd



Function Timer1



	ExecDos::isdone $handle		; return 1 if application have exited, 0 if still running, -1 on error

	Pop $0

	IntCmp $0 0 processfound error processnotfound



	error:

		MessageBox MB_OK "ExecDos::isdone failed."

		Abort

		

	processnotfound:

		${NSD_KillTimer} Timer1

		EnableWindow $R1 1

		EnableWindow $R2 1

		EnableWindow $R3 1

		;Goto END



	processfound:



FunctionEnd



Section

SectionEnd

Thank You.

I guess

ExecDos::exec /NOUNLOAD /DETAILED /ASYNC "C:\Program Files\FAR\Far.exe" ""

may help. Probably /NOUNLOAD required for isdone.

Yes, tried quickly adding the /NOUNLOAD after isdone and it didn't trap yet, thank you.

I didn't even think that isdone could need that parameter too, because there were no mension of it in the help page.

I'll be testing this more closely in a bigger script tomorrow.