MSI will not install; Bundle status is "Downloaded"

Have been receiving numerous "Error impersonating configured user." messages.
I changed the bundle to "Run as secure system user (don't allow system to interact with desktop)" and changed the "Install MSI" action's "Install Parameters:" to from /i to /im. ("Install MSI" is the only action.)
I then incremented the version number. "Install Options" are set to "Install always".
The bundle status in the ZENworks Adaptive Agent is shown as "Downloaded" and the .MSI does not run.
The clients PC's use Windows 7.