Package Execution Fails In Windows Service But Runs Fine As A Windows Application.

I am attempting to write a Windows service that watches a database for uploaded files to import. When a new file is found, the corresponding SSIS package is run from the file system with variables passed through. I started development as a Windows app and copied the functionality to a service.

The app runs fine. The service does not. I get a "Failure" each time a package is executed. Everything is identical behind the scenes with the obvious exceptions that OnStart and OnStop handlers are buttons in the app. I added a script task at the beginning of one of the SSIS packages to notify me that it is even running at all. It doesn't even hit that initial task.

Again, the app will run all packages just fine. The data is imported and the results return as "Success."

The following is the code executing the package. Any help is appreciated. I've been banging my head on this one for a few days now. (Is there a tag to format a code sample?)

Dim pkgLocation As String
Dim pkg As New Package
Dim app As New Application
Dim pkgResults As DTSExecResult

pkgLocation = sPackageFolder & PackageName & ".dtsx"

pkg = app.LoadPackage(pkgLocation, Nothing)

Dim vars As Variables = pkg.Variables

vars("ImportId").Value = ImportId
vars("ProductionServer").Value = ProductionServer
vars("ProductionDatabase").Value = ProductionDatabase
vars("SourceFileName").Value = FileName
vars("SourceFilePath").Value = FilePath

pkgResults = pkg.Execute()