I tried setting the properties on setup.exe to "Run this program as administrator" and got the same results.
FYI, GetExtendedErrInfo reveals ScriptFile=C:\CodeBases\isdev\Script\ISRT\Src\Service.rul LineNumber=327 Error=5.
Right... when I use SC QUERY in cmd window I don't need to elevate the process.
I tried ignoring the result for 'ServiceExistsService' and proceeded to execute 'ServiceGetServiceState'. That fails too. In that case GetExtendedErrInfo shows ScriptFile=C:\CodeBases\isdev\Script\ISRT\Src\Service.rul LineNumber=357 Error=6.
I don't think it is a Vista permissions issue because after I get these errors I can "LaunchAppAndWait" a bat file that stops, uninstalls, reinstalls, and starts MSDTC (which I was hoping not to do if it was already running, but it seems I can't detect that). So it seems to be a problem with ServiceExistsService and ServiceGetServiceState.