You should use the parameter $objecthandle$ and then pass that object handle to your session.init call. That will connect you directly to the session and from there you can call session.companyid to get that information.  Search the forums for $objecthandle$ for more detailed answers on how to use it.

I use Sage 300 2012 and it only works with Sage 300 2014 at least

Write a Sage macro that will call your application. Then you can pass the company from the macro's session object.

Okay can you give me an example, pls

Shell "pathToYourExe """ & AccpacSession.CompanyID

Shell "PathToExe" & " " & AccpacSession.CompanyID

Thanks so much

So for System

You're not experimenting enough

AccpacSession.Organizations(AccpacSession.CompanyID).SystemDatabaseID