I applied SP2 to my Zenworks 6.5 server today. There is a newer version of
the Desktop Management Agent. I would like to push this out to existing
workstations that already have the prior version and run Application
Explorer at startup.

The documentation states basically:

Copy the .msi to a location where NAL can access it (done)
Create an application object pointing to the MSI file (done)
Associate the application to the users you wish to have it, and ensure that
the "Force Cache" option is checked (done)

When the user on my test computer logs in, this error comes up:

Failed to cache application (app-name.OU.O.Tree)
Error code was 2

I can't find a list of Zenworks error codes to tell me what's going wrong.
Any ideas?